Customer service absolete

I have just spent about 50 min on the phone trying to get MTN to check a cancellation reference number for me. My husband passed away in August, and I went to MTN store in Cresta to cancel his contract and convert it to pay-as-you-go. This was the 26th August. For three months, the amount for data and calls was deducted from my husband's bank account. Now his account is frozen due to the estate being settled. Yet, MTN did not cancel the contract and continues to send messages for payment. Went to the MTN store in Cresta again and confirmed that the cancellation was logged into the computer last week. I have a reference number. Phoned MTN this morning as I received a request for payment of his account. Phoned MTN service line and was sent from pillar to post, and nobody could assist, as they said I must go into the MTN store again. I don't know what the call centre's job really is, as I can't even check a cancellation reference number because I can't check on behalf of my husband. He is deceased, so I don't know how to check. I'm done. I have submitted all forms personally twice....... I am not doing anything anymore. MTN can continue sending invoices until they are blue in the face...... I don't care. They don't know how to resolve any queries that are not on a piece of paper. No thinking and resolving skills at all. Customer service sucks.