Tekin repairing ESC's? Thats news for me....
Every Tekin ESC I have sent back to them from a quality issue on their part, was replaced with a new ESC and my credit card was promptly charged without them first contacting me. It is easier and cheaper for them to replace it and charge you than actually investigate the issue or fix the problem beforehand. They don't lose any money by doing this since they are charging you a little more than their own cost.
They repaired my RX8. The lead to the receiver got pinched and need a new one. I don't trust my soldering skills for this kind of work so sent it in and they installed a new lead, same ESC.
Not sure if they repair more serious issues or replace.