Unable to get assistance from Mtn to settle my account

My contract ended in November with Mtn and when I checked my credit score I found out that I have Mtn that is being handed over to legal,I then contacted Mtn to find out what’s happening and I was told that because I didn’t cancel my contract when it ended then I’m charged monthly as a result my account is being handed over,okay now the problem is I can’t get anyone to assist me to settle whatever they want me to pay,I just want to settle my account and part ways with Mtn but it’s so hard to get assistance to settle,the call centre keeps promising me that someone will call and they never call,when I ask for legal contact details no one is able to provide,when I ask them to debit my account to settle that amount they are also unable to,I ask for account details to make a payment,I still can’t get help,What does one need to do to settle this contract,I’m so frustrated because I can’t be handed over for a stupid thing like a cellphone contract,my contract has ended even!Please help ***