Knight Estates poor service

I rented a unit from Knight Estates Roodepoort. My rent was always on time and I was an excellent tenant. I moved out on 28 July and still I am being billed for utilities (meant for the new tenant) from after this date to September. I have sent numerous emails asking for this to be rectified and still haven't received an explanation for this. I was also billed for the utilities for period 28-31 July after the agency advised that the remainder of the days utilities would be billed to the tenant as they had already taken occupation during the afternoon of 28 July. A request for any response was delayed and bluntly ignored when I did a follow up on my emails requesting for feedback that matters will be resolved accordingly within a reasonable period. A final email was send to request urgent feedback within 24hrs yet still no response.