Disgusting service from FNB

I have been a client of FNB for 28 years. I am based in London and incorrectly entered my pin on online banking and was blocked. I have been trying for 3 weeks - gone through countless call centres, private clients and numerous consultants to try to resolve this matter. I even sent someone into one of the branches to assist. The service at FNB is the worst I have ever experienced - it is a “computer says no” system where the left hand doesn’t know what the right hand is doing. I intend to escalate this as far as possible and as many social media channels that I can use to voice my disgust at the service of one of their private clients - I will. I would recommend never using FNB, opening an account or having anything to do with this bank