I would have expected them to ask me to message them, in order to resolve the issue of not having access to my old email. Instead, they assume that I still have access to it, by simply contacting my email provider!
If I could do that, I wouldn’t have lost access to it through would I?
I doubt bruteforce has been used in one of these attacks. The service should detect a bot entering many combinations per second.
The main problem with SMS is that someone could social engineer the mobile operator support to give them a new SIM.
Probably not something you should worry too much about unless you are in any way a target, but still.