Default Where to buy Original HTC Salsa Battery?

Hi Mates,

I had some issues with my htc salsa's battery so I bought a new one from local vendor (As it was not available at HTC service center).

But that battery also didn't work for long and starts bulging so I remove it from my phone and now again I have to buy a new battery.
Can anyone guide me from where to buy it?

Thanks in advance