CANCELLING OF CONTRACT

My Grandfather passes aways on November 06th, 2022. I went to my nearest store to try and sort out his account, but at that time they had loadshedding and was advised that we need to come back at a later date. I went back the following weekend and was assisted by a lovely consultant. I have emailed all the paperwork required through to them in order to have the account moved over to my account as from November i have made payments towards the account. I have been trying to have this sorted out since then. About a month or so afterwards I was emailing the consultant that originally assisted me in store but did not receive any feedback. When I went into the store, I found out that she no longer works for MTN and that nothing has been done with my grandfather's account. I have been trying to get this sorted out and is getting to a point where I now want to cancel the contract as it has lapsed in March of this year. I was told that I cannot do that as there is an outstanding amount on his account. I find this very hard to believe as I have the proof that payment was made towards his account. I am very disappointed with the level of service that I am receiving from MTN. I have emailed customer service and the legal department regarding this matter and NO FEEDBACK IS BEING GIVEN.