Dissapointing service from relationship banking!

I have been banking with FNB for the past 11 years and have a suite of products with them. I am now frustrated to a point where I am shopping around for another bank. I am trying to change my surname after marriage and it is proving impossible! I went into a branch on my banker's advice so I can be verified, unfortunately I did not get help as the consultant advised he needed a certified copy of my marriage certificate. I then called my banker and explained that I have lost my original marriage certificate (version received at church after signing on wedding day) and therefore cannot have the soft copy I have certified. I do, however, have an ID card in my new surname issued by the Department of Home Affairs. My banker requested the uncertified copy and verified/authenticated me using my card and pin and promised to revert to me once she's checked with her manager if she can have my name changed. I was disappointed yesterday when I learnt that my name cannot be changed on FNB systems as this document (recognised by dept of Home Affairs) is not acceptable in FNB standards. This is preventing me from opening new banking products that I currently need. I also received a call from a manager who also did not seem to have a solution and instead just emphasized their processes. I do understand the need for controls to safeguard both the bank and myself but I honestly believe this is ridiculous! (1)I went into a branch with my original ID card and the consultant could verify me. (2)I have sent my details to my banker whom I have been contacting for various other banking needs. (3) I have been verified using my card and PIN. (4) All my other official documentation address me in my new surname. I believe these are sufficient controls for the bank to identify me and confirm that my instruction is legitimate and it's not unreasonable to expect my bank to be able to act on my request, particularly being in a relationship banking space - otherwise what is the point really? I also know that banks have capability to link to the dept. of Home Affairs systems and verify my information. I am hoping this reaches someone with authority who can make a decision to accept my documents as proof of my identity - especially because the only authority in name changes (Dept. of Home Affairs) has. I still have some loyalty to the brand left and do not want for this to mess the relationship built over the years.