Worst service ever!

I started a new job about three months ago witch required me to start using my FNB account again for my personal convenience. I went to cell c Shelly Beach to change my debit order details witch they then so called did. A month later the messages and emails of harassment stared that my debit order had failed and i need to make arrangements for payment witch i paid to their account. I went to the Shelly beach branch once again to question my details not being changed as requested, they responded that there might have been a error on their system and proceeded to change this again! I asked for a reference number this time, their response was that they cannot provide me with this, i insisted on a reference with witch they responded i need to provide my banking details for this ( after changing my banking details). Its now another month later and i still have the same issue. I phoned customer service to try and sort this out ( waited 17min for my call to be taken) . She then asked me questions for security purposes and then changed my baking details again! I queried the R70 fee they want to charge me for failed debit order as this was not even my fault. Issue unresolved :(