100% of fraudulent transactions have gone through silently on my card. Despite the fact that many times my bank has sent me an SMS querying whether something was kosher. Doubly perplexing because they were OS hotel and airline charges, I had a stream of local transactions (fuel, supermarket), I very rarely pay hotels directly, and the bank makes it easy to tell them you are going OS.

After much drama they refunded me. The hotel didn't seem to even care -- presumably they were not getting a huge charge back. IDK if it was a 'card not present' or what. They couldn't even tell me the name of the person using my card -- privacy rules.

Maybe switch banks? My experience is I've had my account blocked exactly once - and that turned out to be actual identity theft. In the end, I didn't permanently lose any money thanks to the system working as intended. On one other occasion, I received a phone call from my bank inquiring about an unusual charge. I confirmed that this time it was a legitimate transaction I made and neither the account nor transaction were blocked.

And my bank blocked 3 fraudulent transaction for me just yesterday. I still have my card, and I had not used it online.

No idea how they got the number.

But it does actually work sometimes.