Again ignored by Telkom

There was a problem with my telephone connection which was repaired (could not received calls). On the invoice of 21/6/2015 they credited me for service interruption with R325,44. The period of this account was from 21/6/2015 to 20/7/2015. The invoice of 21/7/2015 indicates that the account was for the period of 25/6/2015 to 20/7/2015 as well as for the period 21/7/2015 to 20/8/2015. On this account it seems that they took back the credit of the first mentioned invoice. Now this looks to me very much like duplicate billing for June. I immediately logged an online complaint on the 25th of July, which was ignored. After that I logged 2 online disputes and another complaint on the matter. Up to now sounds of silence from Telkom. I want an explanation for these two invoices from Telkom please. Again, I think it is exceptionally rude and bad manners from a service company just to ignore their clients