Telkom excuses

Got in contact with telkom yesterday to ask why they were double billing me each month only to find out that on the 3rd of each month your account is automatically being handover to a debt collector.When I ask how that is possible as telkom debit there money end of each month they told me because my payday is month end it dont reflect on the the 3rd.When asked why they didn't share that important information upon starting my contract with them ,they told me "well you should have known",and I ended up paying over R1000 last month.I told them it was madness as my installment agreement is R450...I'm so mad at Telkom and will never ever do business with them