Lost cellphone number

My mother's number was suddenly taken away from her and in panic thinking that it was one of these ****s where one's number is swapped to use it to commit ***** we phoned MTN only to find out that they were aware and promised to return it to her without any success, she has been having this number for years and all her contacts have this number and now they cannot get hold of her , what an inconvenience. I thought I should come on this forum before we can contact ICASA to seek comfort because we failed trying to get MTN to rectify this mishap and utter disregard for my mother's rights as she paid for this sim card and number.