MTN Retentions Department Not Doing Their Job

My previous contract terminated in October and I also requested that my contract not be renewed because I want to use pay-as-you-go until I decide to again take out a new contract. The old contract was terminated as requested but then MTN put me on a new 2 year zero rand contract. That now prevents me from taking out a new contract and after several calls to customer care and reference numbers being send to me, nothing has been done yet to cancel the zero rand contract. The number the call centre agents give me to call the Retentions department is never answered. Below is the typical email response I every time get:

It looks like we lost you somewhere during your application.

A call centre agent will be in touch to complete the process. Your reference number is ***1 If you need any assistance please call 083 135