Unable to change from a contract to prepaid

Hello my Mother has been trying to get hold of the mtn contact department since yesterday. Whereby she has finished paying for the contracts which she took and now she still wants to uses the same numbers. Both the numbers have been deactivated since she wants to change them to prepaid. She is currently unable to receive any calls. Plus the mtn call center are not even able to help her out when she calls them. I'm very disappointed with their service and the way they handle there customers. When call 135 they tend to say they'll transfer you to the contract department then they just hang up the call without helping her. It's now been over 24hr since the numbers have been deactivated by mtn.