I have not received my Refund

Location/place: Bangalore

Name of company/service: Bajaj Finance

My LOAN DETAILS – 4040PL00145353

I have closed my loan my paying through online and still there was a excess debit of my EMI 3344, I followed from APril 30th
and I received a chq of 2681 on 28th may , instead of 3344/- when I deposited a chq in to the bank , the same was bounced back with the reason as one of the signature is missing.

Then tried no of times to the bangalore branch and there will no one to pick the call.

I have send so many emails , but still I have not received my refund back. Hence kindly I request to solve my issue and get my refund back