Breach of contract

In November last year my contact came up for renewal. I got a better deal with Vodacom and decided to move over to Vodacom. When I called MTN to cancel, they asked me the reason for my cancellation. After explaining to them that Vodacom has offered me a better deal, MTN offered to give me the first three months of my new contract free. To date 8 September 2015, almost a year later I am still waiting for the three months credit. After numerous emails to them via there store in Canal Walk, I learned that the credit was approved in December, but not passed yet. The reference number: is ***. Someone is not doing there job as all the emails that was sent off to retention department are still on their system. Another email was sent off to retention department on 6 September and that ***. Why do I have to wait nine months for a refund with numerous reminding emails? Can I please just get my credit of R1211.96 as promised. This became part of the contract, otherwise I would have moved over to Vodacom.