Zero response from MTN branches to numerous requests to increase my package on Cell number ***

In May 2017 I did a renewal of my MTN contract at Ballito Junction. The lady who advised me suggested going onto a lesser package based upon analysis of my usage over the prior 12 months. I took this advice but then found in August 2017, that I had run out of airtime. I went to MTN Nicolway to request an increase in my package to increase the amount of Airtime. No response. On 27th December 2017, I went into MTN in The Mall at Somerset West and made the same request to the lady who served me. She promised a response within a week and as of today's date (24th January 2018) I have had no feedback. I am willing to pay extra to accomodate my needs and as an MTN customer since the mid 1990's I expect some level of service.