Incorrect billing info

Cell C contract for number ********** 414 used to belong to my husband which passed away on the 7th of March 2017. We had this contract transferred into my mothers name CV Smith and from them we have numerous calls and sms's stating that the account is in arrears and will be handed over. The amount of R595.66 was settled and proof of payment send through to the legal department and still receiving the sms's that the account is in arrears. We have been to Cell C stores 4 times to see if we can sort this problem out and everytime is informed that nothing is outstanding on the account but the numerous sms's we receive is beginning to be an irritation and just want this to sorted and confirmed once and for all that everything is up to date. The reference number on the sms to note if making payment is ********** 72.