Vodacom bad customer service

Took out a contract a year ago at Vodacom to get new devices as I was still on a contract with a different network I had to wait for that contract to finish before I started using the Vodacom sim cards or else I would have lost all the benefits from the other provider. Want to port my old number to Vodacom now as that number is on prepaid now and they say it cant be done at Vodacom.

So now I either have to let my old number go and I really don't want to do this or I must just not use the Vodacom sim and the benefits I'm paying for every month.