Summer Mobile misrepresent MTN contracts and do not respond

During February I was contacted to renew my cell contract. I was promised that the contract in terms of minutes and data would remain unchanged. 6 weeks later when the airtime and data was provided, there were no data and the airtime was changed. On top of that accumulated airtime from the previous contract was removed. I have now been struggling since early May to try and get this resolved. Until 25 May there was no response (3 weeks)