Unfair billing after account closed

Good day, I would like to request that you kindly review the below complaint that I have for MTN who continues to bill me for January and February 2021 when I receive confirmation on 13 December that my account will be closed - therefore making end December my last payment (it was also the end of my 2ye contract) I am currently living in Canada and was unable to call them but sent numerous emails and messages via Twitter and Facebook with no resolution- but that I now owe them R1100 for January and February and I do not have any funds in my SA Absa account. Can someone please assist in resolving this issue? My reference number were 391112 and ***. I have not received a response since my last email on 8 March. I received another statement today showing I still owe the R1100.