MBD contact is bad and cannot get hold of them

I have a Standard Bank Credit card that I have been paying each and every month since Sep 2018 and this was after I was retrenched and fell behind on my account. So this account has been handled by another law firm and as I have mentioned, I have been paying. This morning I get a call from ***, but their line was so terrible and I could not hear a word the person was saying. Then after that I receive a SMS from MBD telling me that I promised them I will make payment, otherwise further legal action will be taken. So I sent an email to *** asking to explain what is going on, but to no surprise, I have not had a response and I doubt I will get one. So I called the number I was given on the SMS ***, but what a waste of my time, the automatic answering tells me my call will be answered in about 1 minute, however after holding for over 10minutes, I decided to drop the call and then I called back to opt for them to call me back. Then 3 times they call back from the 066 number, but once again I cannot hear a single word they saying and then the call gets dropped from their side.

So what I need to know is where did I make a promise to MBD for monthly payments if I have already been paying and then also MBD sent me another account number where I must pay the monthly installments which is different to the one I have been paying into from 2018.

I am not happy and I need someone more senior to make contact with me as I do not want to talk to a call centre agent as they cannot help me.

I also completed their online "contact" form hoping someone will call me back, but once again I doubt that will happen.

I am seriously not impressed and need answers.