FNB strikes again and inconvenience me

I am writing again with the delay and dissatisfaction from FNB in dragging my disputes. I still do not understand why my orders gets cancelled when using FBN for online purchases. I have submitted proof that was required including emails from the merchant stating that FNB withheld my transfer as to why I do not understand. The amount is reserved for purchase on my side but according to merchant it’s pending pre authorisation with FNB. Who gave you a right to do such because you inconvenience me and my plans also messing my account. Please fix this mess you created asap before I escalate it to ombudsman