Disgusting customer service

I have a problem with an airtime that I bought on Thursday(05/10/2017). The airtime had a problem so I contacted mtn, I was told that they couldn't help me as I'm not using prepaid. I emailed them with the details of my query however they are still sending me from pillar to post. I fail to understand why they are doing this as I'm a paying client. To this day no one assisted me.