Charged for items that don't exist

Received my itemised billing for April where I was charged R86.84 for an item with no call duration and no telephone number on the itemised bill (ie fields were blank). Raised the query with the call centre - after 17 working days I called back to find enquire the outcome (since no one bothered to close the query with me) - the consultant noted that the query was closed and that I would not be credited - NO FURTHER EXPLANATION WAS PROVIDED. I disputed the item once again and was told to call back in 7-14 working days to find out the outcome. Firstly this shows incompetence since no one called me back to advise that the query had been 'closed'. Secondly the reason for the closure of the query is inadequate. Please do not provide me with a standard response that \someone will be in contact with me shortly"if you don't intend to actually follow up on this for me."""