How lose your customer

I am disappointed with FNB. I have had a credit card with them for around 35 years which has always been in good standing. My outstanding balance for last month was R1742 due on 19 May. I was travelling on business and missed the payment. By Saturday they had blocked the card. Its never happened before if I was a few days late. No call, no email, no sms reminder. Just cut you off. Our banks still have no idea on how to treat their customers. Imagine if a normal business treated their customer of 35 years in this manner over such a small amount. I have 12 business accounts with FNB. Maybe time to change but sadly most the banks are all the same.