Overtank Boosting 

These guys are epic. They know what they are doing and they are doing it more than great! I was very very
skeptical and worried about my account/money but there is no need to be. I gave these guys one of the hardest tanks to mark (probably the hardest one) and they still done it in kinda short time. Also they are 24/7 on the support chat ready to answer any questions or update you about the progress. Im pretty sure i will use this service again in future.

Did a lot o research and finally decided to go ahead and i was right, quick communication, great service and i will be back for more in the future.
Edit and updates
The site states :
All missions are done with honors! If you do not need any mission with honor please ask for a discount on our 24/7 live chat!
But this is not the case, they no longer do the missions with honors so if it's important for you guys the look somewhere else
Asked twice the support on chat and got this answer

Great tutoring and platooning. Play with the best, maybe you get better. I learned a lot from it. Highly recommend it.

Verry bad service , i had ordered 50 battles ... took them a verry long time to finish it . Prices are verry high compared with other service providers. i wont use it again.

Was very well done and fast. Very pleased with how it worked out, would use again.

excellent work and fast service. well communication and everything achieved in timely manner. will recommend to all

Ranked battles completed in 3 days, excellent service, loads of credits, bonds and all 3 divisions done, great communication and very professional. I was sceptical but please dont be, amazing service.

This is my first time using their services and I can highly recommend them. I used their services during ranked battles and was very happy with the results. They communicated with me every step of the way and completed their service quickly. I will definitely purchase from them again.

Excellent, fast and proffessional work. Silver league in 3 days. I'm very satisfied with the services of Overtank. Definately will order again.

I bought the Excalibur Union 14 mission, it was late at night so I didn't expect it to be done today, but it was! It only took about 45 minutes (if that). I will absolutely be ordering again soon! Object 279E here I come!

Wow, I m stunned! Mission completed, got my first mark on su-130PM, earned more than a million credits and got great wn8 + more than 10 t55a missions completed for only 20$ Incredible job done and I will 100% buy more things on this site! 5 stars from me!

As a first time customer, i am pleased with the over all out come and performance. However the win to loss ratio was worst than my own which is a shame. I would have thought that a Unicom player would have made more wins as he / she is doing a lot more damage over all. And may i say that even i hit 3000 plus at least 4 times a week over all so would have been nice to get more wins. I will however use you again for help within the game, but see some of you're prices are way over the top and would never use, and that's a shame really. I look forward to using you're company again in the future. Helpful staff good understanding of what the customer is asking for.

They did a great job on my list and man I'm happy.

While i was abit sketchy on to trust overtank or not i wanted a T10 tank so i just went and paid for it + 10M credits and after 10 or so days i had gotten an email confirming they were done and i was able to play :) 10/10 would recommend using overtank and will deffs be buying again ^.^ Thanks Boris, Marcus and other staff who have helped me out.

Took 2 days from order to completion of TD-15 for T-55A with honors, including queuetime. Got 1 mark of excellence in the process, though I was already close. Very simple service, order, pay, wait, done. Will 100% come back if I need something else.

Asked for 2 279 missions , less than 24h later it was done, what else can I say ? GG and thx

I had reservations about my orders because I was not sure entirely which packages would fill my needs. Boris and his Overtank staff walked me through my options and even showed me some ways to combine items to get more results for less cost. Boris' technicians completed my order in a reasonable amount of time and they were on the account during my day hours which freed me up to play during the night. Their average game quality was about 2300 Win 8 over the 750 games needed to fill my order and I was left with many million free exp and my new tanks. Excellent company and very professional.

So far, so good. Responsive, professional, timely!

I ordered 20 battles played at +5.000 WN8 on the T34. When those battles were played on the T-34 (Soviet medium instead of the US Heavy), I notified customer support and Boris took care of everything. I am always impressed with this service and will continue using it.

Ordered several Chimera missions from Overtank; even though I didn't meet their required criteria (was missing a tank or two) they still managed to get the missions done in just two hours. Support team through the live chat was excellent, and games were played at a high level. If you don't want to tear your hair out over a stuck mission, then their services are definitely worth every penny.