I got an SMS like this many years ago from Capital One on the same basis, and it said to call a specific number if I had questions... I couldn't find that number anywhere online or on their site. It took forever to find their fraud hotline on the website, too. Different number to the one in the SMS, naturally.

Turned out to be legit, and they were calling about a transaction at a gas station that I had actually been to. But the fact that I had nothing to go on except a text message from an unknown number was super suspicious.

These banks need to realise that there is a difference between customers trusting their brand, and those same customers trusting some random message claiming to represent their brand.