Vodacom Holds me hostage

I cancelled my Contract with Vodacom on the 29th February 2016. Settled my account , at the time I was on a month to month payment , despite using a small fraction of my air time and data , Vodacom failed to credit my account. To add insult Vodacom has prevented my number to port to another service provider. Despite calling at the Clear Water Branch as well as the customer care on numerous occasions no one has been able to assist. I have logged two complaints which have been ignored with the exception of an sms that they will revert back to me with in 24 hours , I am still waiting. Please can Vodacom explain why they failed to credit my account with air time and data when I cancelled my agreement and why every time I try to port my number , the request is rejected without an explanation. When can I expect this issue to be resolved so that I can have the number ported?