My Online Shopping Account Suddenly Locked After I Tried Adding a New Payment Method

So, I was updating my payment info on a popular online shopping site last night because my old card expired. I carefully entered my new card details, double-checked everything, and hit save. But instead of confirming the update, my account got locked with a message saying suspicious activity was detected. I tried the site's help chat, but they just gave me generic advice to verify my identity, which I already did, and now I'm stuck without access to my orders or saved addresses. I’m worried because I have some pending deliveries and gift cards saved that I don’t want to lose. I even tried logging in from a different device and cleared my browser cache, but no luck. Has anyone ever had their account locked like this after updating payment info? What steps helped you get it unlocked without jumping through endless hoops? Should I be worried about someone trying to hijack my account or is this just an overzealous security system? Any tips on how to prove my identity more effectively or avoid this kind of lockout in the future?