Trying to cancel a MTN contract which was on my mothers name who passed away on the 4th of March 2017

We have been sending emails to cancel the contract which was on my mothers name who passed away on the 4th of March 2017. I have phoned MTN as well on number "808", then choosing option 4. The operator gave me the following number to phone ********** 920. When I dail this number the call ends everytime before the phone rings. I have struggled with MTN to cancell the contract and to transfer the cell phone number over to a prepaid number. Can MTN maybe come back to me on hello Peter since they do not come back to me on email, nor any phone calls. No one at MTN can help me, I need advice on how to proceed with this matter because I really don't want to go the MTN on 14th Avenue and make a scene there in front of everybody just to get someone to help me. MTN can you please help me to sort out this matter without any further delays or any unneccesary actions.