PartMaster poor service

Hi Guys

i purchased a battery from PartMasters. i simply gave my laptop model no and was not asked for any further clarification / model nos, etc.

the wrong battery was delivered. PartMasters agent insist that it is the right battery and that i should foot the bill for the return shipping as the mistake was not theres. so is the mistake mine?? i gave the laptop model no as written at the back. how is this my fault??

pls assist