Debitting account despite Notice being Given & taking way too long to resolve

This review is for my sister who works irregular hours and who may not be contactable and has asked me to assist. Some Months back she gave notice to CellC to terminate her 24 month contract that was expiring. Cell C did not do this and she only recently noticed that Cell C were still deducting monies from her. 4 weeks ago she contacted Cell C and matter is still not resolved. She has followed up with Cell C and now has finally got a reference from them. Cell C have stated that they are looking at call records but this again can take some time as she did not originally take down the reference number and cannot recall the exact date and time of call. She is adamant that she gave a months notice to terminate. The reason for termination is because she is now on a Cell C "share contract" with me. so bottom line is that the customer is not lost to Cell C!! Surely Cell C can fast track the whole process by simply checking usage on the MSISDN. Also, I trust that Cell C will immediately terminate the contract and not see fit to apply another months debit because of notice T&C.!!

Information and actual client/case detail is included as Additional Info. A/c: ********** 24 My contact number is given but alternative contact details of client can be obtained from Reference Case.