Waiting for tooo long for response on cancellation

I upgraded my internet modem at Autopage but at that time they did not have stock. They would call me if they receive stock which never happened. After two weeks I phoned and was told they merged with MTN and I must wait until 17 March 2016 and query with MTN. I did that and phoned them so they told me to go to MTN store and do the request. Which I did. Lady helping me, name is MPHO and she went out of her way to help but as it was upgraded on the system it needs to be cancelled first before she can do the upgrade again and give me my device. I phoned and they told me will take 48 hours but its almost 3 weeks later and still its not been done. Mpho (Mtn - mall at Carnival) keeps on sending emails but with no response. I long must I wait for a cancellation to be done?