Vodacom not releasing my cell number

I have been on Vodacom contract for many years and decided to move over to cell c contract. I closed my account at Vodacom on Monday 4th March and paid the account in full. Cell C have ported my number over so I can receive all calls except Vodacom sms'ses and phone calls as Vodacom haven't released my cell number. We have phoned numerous times, even cell c porting department have phoned Vodacom porting department and receive no response to release my number. Vodacom have no right to keep my number anymore.