State Bank Of India [SBI] — fraudulent transaction on credit card and phone no. associated with credit card was also changed without customer consent

1. Registered contact no. linked with credit card was changed with another one without my consent.
2. Due to this some fraud transactions was happened with my credit card by Paytm and Amazon pay on 16th January 2019 as per bank.

I came to know about all this when i got a call from SBI Gurugram office that, some multiple paytm transaction initiated through your credit card, so is it you or someone else, i asked him to block transaction as well as card as it was not me, then the person confirm me the mobile no. which was also not mine . So i ask him further procedure to log a complaint, he suggested to call helpline number.
After this i called SBI card customer helpline and i told him the above scenario, i again confirmed that the card is blocked or not and what transactions are happened till now . The executive confirmed that no transaction is happened till now and card is also blocked. I also ask him to log a complaint for the same. This was all happened in January .

After all this in march some of recovery agents came and said that all of your credit limit is used which is 1.66 Lakh . I told him the whole scenario, but they are keep calling and asking for money .
So i want bank to investigate how the contact no. was changed without any of my consent and just refund all the transactions happened