Mweb accounts

Having trouble with the accounts. They sent me a statement on the 12-2-20. It was paid the next day. But I am now contacted by some law firm acting on their behalf. I contacted the mweb call centre and was told I was in credit. Their one time pin is not being sent so you cannot contact the accounts dept. I had to go through the new sales channel to get some info. The one operator after explaining to him the one time pin problem he then put me back into the digital wonderworld where a one time pin is required. If the law firm proceeds with their action and my credit rating is comprimised there will be backlash.