HDFC Bank — unauthorised emi loan created by hdfc bank against my credit card aggregator emi - offus

Address: SN 34 & 5, Sreeji Cplx, Bedford Circle, Nilgiris, Tamil Nadu 643101

I had made a purchase on Flipkart on 25th December using my Easy EMI HDFC Credit card. I however cancelled my purchase and had the same amount credited back to my Credit Card. On 31st Dec, an AGGREGATOR EMI - OFFUS transaction been made. The credited amount not been adjusted with my Unbilled amount? HDFC has processed an EMI without my authorization and there is absolutely no way I can reach them over a customer service number.
On 4th Jan 2021, I received another email that the Loan had been approved, - Subject of mail, " SMARTEMI LOAN AMORTIZATION SCHEDULE ..."
I repeat, I have NOT opted for any EMI loan.
How does HDFC take the liberty of inconveniencing its customers in this manner. I hope necessary action is taken to get this resolved. I have written a second complaint on their website, which most likely will go unattended.

Russel Antony