Panasonic — didn't get my phone battery & customer care is not refunding my money back

Address:

Bardhaman, West Bengal, 713216

I visited a customer care in durgapur because my phone was not working. They told me that the battery is defected, so i ordered a battery from that place and they took rs400 as advance. And told me to come after 1 week. Its been 1 month but i didn't get my battery, so i asked them to return my money back they refused to return. I am stucked very badly i can't buy battery from any other place.
Please help me sir asap.
Thank you