Worst network provider ever

I recently took out a prepaid fnb connect sim card. From the first day of taking it out I had major issues with FNB like porting my number to the wrong account. We eventually had that sorted out. However the problems continue. DAY BY DAY my prepaid sim card goes into a negative balance. The rates of calls and data charges are 20 times larger then for example vodacom as I use data for whatsapp messages only and purchased 500 mb in 7 days, lord knows where that went to. My purchased Airtime also just drastically decreases without usage. Worst network provider ever.