What places fix over-ear headphones?

[That awkward guy]

So I have these Monster DNA headphones and I can only hear one speaker work at a time, if I connect the aux cord to the left speaker, I only hear the left, if I connect it to the one on the right, I only hear the one on the right, anyone know if I can get them repaired? If I can, where will they repair them, and how much would it cost?

 

[Reynod]

You need a splitter Y cable to connect to PC's that have the newer 3.5mm 4 pin.

http/www.ozgameshop.com/pc-cables-and-ports/3-5mm-4-pin-to-2x-3-pin-3-5mm-headset-splitter-adapter-m-f?utm_source=google&utm_medium=shopping&utm_campaign=google+shopping+data+feed+(31/12/2015-09:40)&gclid=CMmx6uLAmcoCFQF_vQodn8UNFA