MTN total ***********

I took a SIM only contract I used to pay it via the MTN app when I lost my phone I couldn't pay I went to an MTN shop in standerton they refused to help me stating that my contract was on the older version of a system they using..they cannot access my data I called the call center no 1is able to assist me..now unfortunately I'm in default and it is affecting my credit record I was decline a chance to apply for a home loan because of that .. I'm devastated and tired alrdy