Harassment by FNB and TS LEGAL

I am still being harassed by TS legal regarding a credit card that is not mine, I have an arrangement with FNB of paying my credit card R800 every month which is what I'm doing, I don't know why I keep receiving this harassing calls from this attorneys of FNB , I can't take this anymore, we are going through a lot with the coronavirus which has affected us dearly physically, financially and emotionally and on the other hand there are people who keep on harassing us and worse about an account that is not mine. I am paying the account as per the agreement and still it's not enough. I'm sick and tired of this.