Bad service

I am 1 and a half weeks away for an eligible upgrade with Mtn and they refuse to assist, I am out of the country soon and would like to upgrade my phones prior to departing, I also paid up my monthly account and they arent willing to assist a long standing customer of 10 years for an upgrade, I have sent numerous emails to the retention department with no joy, id think it would be better to just cancel my contracts and move over to Vodacom or cell c as they seem to provide a much better service than MTN, if MTN is willing to assist here is my info below: Y Bissoon numbers for upgrade : ********** 788 , ********** 657