FNB avoid taking responsibility for ***** on my account

In December I discovered merchandise is deducting money from my account. 1. I logged a complaint with FNB. Their response to me: I must contact the merchandiser. ( Which is impossible seeing it is unknown, I do not know who to merchandiser is how must I contact them?) 2. I logged a 2nd ***** claim. This took the bank 6 months to respond!!!

Their response to me: "We regret to inform you that we are not in a position to accept liability for the costs incurred and have no alternative but to hold you responsible for the transactions debited to your account. FNB hide behind the fact: “Statements should be checked for accuracy on receipt. Any discrepancy should be reported to us within 30 days, otherwise, the statement will be deemed to be correct” ** Keep in mind these are transactions that will require and an OTP from me to approve before the transaction can take place. I have requested proof of each approved OTP transaction** None been provided by FNB!!! IN SHORT - Even though FNB tell you they secure your account with an OTP and that they will release a transaction on a unique OTP ……….. is a false sense of security!!! So, I need to know if someone can direct me in the correct direction, to take this bank on? Or will it mean I need to accept their outcome unless I am prepared to spend more money on legal cost?