FNB is going to the dogs because of KYC

I have banked with FNB (Barclays) since I joined them in July 1972. I have retired and continue to bank with FNB. My wife opened her first account in 1974 when we were married. We have, in my opinion, substantial deposits with FNB and run excellent accounts. All of a sudden some department called KYC have decided to completely mess up my relationship with the bank. My wife operates a secondary card on my credit card. I was requested to send a copy of her ID document as they say they have no record of it. I comp****, they acknowledged receipt. Then they said I had not comp**** and threatened to stop the card. I comp**** again. Answer - the email box is unable to take anymore email. I advised my private banker who said he would sought it out - this was all in the beginning of April. Today they sent me a letter to say I had not comp**** so they are stopping the card. WHO IS KYC AND WHAT ARE THEY DOING. Destroying all the hard work of my Private Banker.