Last year I made the mistake of registering for a presentation....

Last year I made the mistake of registering for a presentation. Didn’t think much about it. A couple of weeks later the calls started. Some young guy trying to pressure me into their “share advisory service”. He just wouldn’t give up. I blocked his number; so then he’d call from another number. At first I was firm, but politely told him I wasn’t interested. In the end I became really angry and insisted they remove my number from their call database. Nothing for about a month, then a different guy called. So I reamed him a new one. No more calls.
So be careful giving out your details, IMO.