RBL Bank — despite i raised a request to stop my credit card services. they didn't and now asking for credit card payment

Address:

Pune, Maharashtra, 410501

I opted for rbl bajaj credit card in july 2017 then i found this card is not usable for me so raise a request to stop its services in april 2018 through call and mail. Then they said they have registered request and will process soon then they came up with my number is not reachable give me ulternative number. I gave that too till they did not call me and now suddenly they are calling me as to pay new year service charges for the card. And interesting thing is that when they call me to pay bill then my number is reachable but when i say i want to close this card and its services they said my number is not reachable. Please help me this people are fraude