ABI and AMEX are not stopping services of my credit card.

Hi Experts, I had credit card from SBI and American express both. I sent emails to SBI more than 10 time to confirm that my account deactivated so i shouldn't be charged but they do not respond back with proper information. I have all the emails communication happened with bank. Same thing with AMEX, i have called 3 time to discontinue the service but it's still active. They says they have sent letter 3 times but i never received and even they don't have information where these letters are going. When it was a credit card they delivered my in next 2 days and now it's discontinuation latter it's bee more than a month. Simply they don't want to stop the account so they can charge for coming year. Unfortunately, i don't have any proof against calls that i made to AMEX because they only have phone support. Can you please suggest me if there are any laws to deal with such condition? Can i file an RTI to reserve bank asking why my account has not been discontinues even after requesting several time? will that work? Please suggest. Thanks, Akhtar Nawaz