Telkom does not have integrity

Last month I was due to pay my account, they sent me an invoice of the amount I had to pay on my debit date but to my shock they debited R300 extra without any sort of explanation. Now In my book that's *****ing outright and to make things worse they sent me this months invoice and they will double debit me because of some past due amount that doesn't exist. I really want out of Telkom because they abusing me as a paying customer, they are more interested in the acquisition phase then taken care of paying customers.