Refuse to cancel my husband's contract

After being with MTN for years on a contract, we decided after my husband's retirement to change to prepaid. His current contract expires on the 23rd of March 2015. After looking at their website for cancellation information, i saw that they accept a minium 30 day and a maximum 90 day cancellation period. I took a screenshot of the information. I phoned the call centre and they told me my husband can go to any mtn store to cancel. Well there our hell started, both the Vredeburg and Cape Gate stores refuse to accept my husband's cancellation, telling him to come back on the 23rd of March 2015 to give a month's notice, taking the contract period into 25 months, if I count correctly, surely if he gives 30 days notice before that time, that means he will switch over to prepaid the next day after the 24 contract period expires. MTN, you are more than welcome to phone me or my husband if this is not true. I then emailed cancellations from the website plus a complaint, but until now, we have not heard from anyone. Can someone please phone us.