I would really appreciate if somebody can help me with the unlock code for my T- mobile HTC WING

Want to use it with at&t sim. 

Model => HTC WING

Model no.=> HERA110

IMIE=> 35286201549864202

It would be great if  you can provide the code.

Any idea and suggestion are welcome, I googled it, one site asked for 20 bucks, 

Thanks in advance,