Refusal to assist

Good day I went to multichoice today to change my cellphone number on the system ,The account is on my grans name who has been deceased for 7 years now ,I took over the account as a 3rd party as I am paying for it .My cellphone was ****** and I received a new number so I wanted to update my new number in order to receive notifications like before ,previous being the 3rd party on the account I never had an issue with changing my number the first time ,so today I get told that I am unable to change to the new number as I am not the account holder and they require paperwork of my gran before they can change my number , I am unable to get all the documents required as my gran has been dead for 7 years and her family only has an ID of hers . The staff at Multichoice refused to assist me further . So today I did my cancellation as I feel that multichoice couldve atleast made that effort to change my number like they did previously as that is all I wanted as I wanted to get notifications .I have been a loyal customer for many years and have never had a problem before with multichoice and they have always assisted me without problems .I feel unfairly treated as I have never missed a payment .If multichoice is so quick to cancel my account without assisting me with just a change of number then I would rather go without your pathetic service I am sad to see you throw away a customer just because I wanted to update my details . Kind regards Marius van Eden ********** 011 acc holder VL Daniels 431 ********** 089