[Resolved]  HDFC Bank — Haven't got cashback of 6000 on purchasing IPhone 11

I purchased an iphone 11 from 'unicorn infosolutions pvt ltd' in pune on 17th january 2020. Hdfc cash back offer was attached with it which promised to send rs. 6000 cash back on paying with hdfc issued debit/credit card within a span of 120 days which completed on 17th april 2020 but i still haven't received my cash back. Due to covid lockdown the customer care service is also affected and i cannot get to hdfc customer care to complain about the situation.
I purchased this phone with hdfc credit card ending with xxxx-xxxx-xxxx-5601 with emi of 6 months. I have already paid emi instalments of 4 months but the cash back has been processed to my account.
Also attaching the invoice of phone purchased.