Debit order

Good day, Yesterday 01 October Telkom took a debit order off my account when 3 months ago I told them to take it of debit order and I will pay EFT once money is in my account. It was going great been paying them on the 2 for the past 3 months and no hiccups until yesterday. Because it wasn't a successful payment got charged R100 for unsuccessful payment because there was no money.