Changing debit order details - does not work

After needing to change my banking details for the monthly debit order (in February 2018), I visited the Telkom web site, found an option to change the details and did so. No information was given about needing 30 days before this was going to be effective. As expected, the debit bounces and an extra R200 is added to the account. Went to the web site again and everything has changed. I find an option to remove the debit order. I use that. Still no information saying 30 days before this might work. Once again, the next collection attempt fails again, STILL using the old details. Another R200 added to the account. So I send an email to Telkom. No response. Nothing. So now I phone them. Details are still old, debit order has not been cancelled, nothing. I have now asked them to remove the debit order, but that still needs 30 days for some reason. So now, I will be charged a further R200 because the next debit is also going to fail. I ask the representative if I can dispute the extra charges, he says no. Well done Telkom, providing ways for people to change details that don't work, and then charge them for that opportunity.