Credit Union not in the 21st century

I had a charge refused on an online purchase I made with a credit card from my credit union on Wednesday. Then it happened with another online purchase on Friday. After that one, I went online and checked my account. Everything was up to date and there was nothing to indicate a problem. Today I tried the card in a store and it was also refused. In this afternoon's mail, I had two letters from the credit union letting me know that both my credit card and ATM card had been cancelled because some company which processes some of the transactions had stored account information when they shouldn't have. Both of my cards were in the range of numbers which were compromised. They are in the process of replacing the cards for many people who have accounts there, something which may take more than a week. The question for me is why did they rely on snail mail alone to notify people. There's nothing on the website and there have been no emails indicating there was a problem. They do have a recorded message if you call them, but it seems to me that they should have covered all the possibilities.