Non response to customer care line

Since having my contract moved from Nashua Mobile I have had nothing but problems and no one to assist. I have called customer care, I have visited numerous stores. My capped data bundle, unused for 3 months continues to attract bills in excess of R6000. Store assistant at Hyde Park incorrectly effected a 'sim swap' on this number in error at the end of August and this remains unresolved. No store or customer care official has been able to assist. Suggestion was for me to email customer care. This I did over a week ago. I did get auto response that the message had been received....waiting. No service but continue to have escalating bill??