Poor service received

I lost my job in April and shortly after wards i called Telkom call centre to inform them that i am no longer working and i have closed my account with the bank since i do not have any income.I asked them to change my payment method from debit order to manual payments.I have been paying my account manually since then and i have never had any problems.I receivec my invoice for this month and it shows that i owe R833 which is due to a +200 fee for a returned debit order.How is it that i am charged a fee for a returned debit order when i have explained that i no longer have a bank acccout?

Another issue that i have,my contract has expired,i requested a cancellation online and someone from the retentions department called me and told me that i can keep the contract on a month to month basis and that my new package will now be 2 gig night data and 2gig daytime data for the same amount that i have been paying.The number used to call me ********** on 2018-10-26.I got my data on the 1st and i still received just 1 Gig.When i call the call centre they cannot pick up our conversation regarding the added benefits.I tried to request a cancellation again now and it is telling me that the is a request already loaded.Can someone please sort this invoice isssue and advise me on the payment that i need to make then please close the account.