Grrr, I HATE dealing with banks, especially by phone- assisting customers my arse! Had something similar happen a few weeks ago- turned out the card was declined due to suspicious activity, they couldn't help me by phone I had to go in, whereupon I found that it was something to do with a crypto site and had to sit through a whole rigamarole while they reactivated the card. Wankers.
Suspicious activity, yeah. Taht seems to be code for we're gonna teach yiou a lesson!