MTN not being able to assist

I changed banks in March. I went to MTN store in Lambton to change my banking details for the debit order for my contract. I was told to phone 808 or 083 1 808 from a landlines which I did more than once for everyday for about 2 weeks, the phone kept advising that they cannot pick up my contract. I went back and was advised I can only do this telepathically. I went back to MTN as my my debit order bounced in March as the debit order account was now closed. I then went back to the Lambton store who advised that I can go to a store to change my banking details now, but they can assist as only some shops can accept the cash payments for the outstanding amount and then switch it back to debit order. I then went to the MTN store in Alberton City where they let me wait 45 minutes before someone even asked me if I need assistance. I then waited in a Que for another 30 min before being advised that they are offline an cannot assist me. I have a small baby who I needed to then by this time feed and could not wait for them to come back online. My account is now 2 months in arrears and i am getting SMS that I will be cut off if I don't pay, yet I cannot arrange payment.