FNB is unable to explain my transactions.

I received an in contact msg on the 28th Dec last year, the amount being R356. I queried this transaction not long after I had gotten the message. All I wanted to know is what the amount was for. I called into the FNB call centre on many occasions . And I still could not be assisted. FNB then confirmed via SMS that the debit order was for a device. I call in to query which device and the call centre agent then tells me it is not for a smart device. I have been given the run around since then and to date, I have not been given an answer to what I am debited for! If FNB cannot answer as to what I am being debited for, I would rather not bank with FNB period!!!!