missing minutes and terrible processes in place

i have been missing minutes after loading airtime and sometimes unable to make calls from my phone , i have reported the problem to the call centre on numerous occasions in the past 2 weeks , they would investigate - refund me the missing airtime only to have that go missing as well , on Saturday 15th July 2015 the same thing happened again when i tried to call the call centre again on the 173 number an automated message advised that i have reached my free calls to the call centre for the month of July and can only make free calls again in August however i can call a certain 083 number to reach the call centre and i will be charged for making this call , how fair is that if their systems were working properly i wouldn't have to call them so often and now i must use my airtime to claim for the missing airtime , that doesn't make sense to me, i have been a loyal MTN customer for the past 15years and have been using my current number for 11 years I'm really considering moving to another network provider ,it seems I'm not the only customer with the same problem as my social network friends also complained about the same thing happening to them,this is really Bad service.