MTN Contract Upgrade Breach

I did a COMPLETE upgrade and even SIGNED PAPERWORK a month before the Lockdown but due to the store having issues with their new system the process took longer then it was supposed to. The store manager was actively involved, trying to assist and also did numerous escalations to get the upgrade done. However, now that all is apparently in order. I have now been told that I can't get the phone for the same advertised price as the promotion is over. During the upgrade the phone was kept aside and the serial number was allocated to me and after all this we are told it was all for nothing. The issue was not my fault and neither was the Lockdown. I am extremely disappointed in MTN. Does the signed contract mean nothing?