I've had a Discover $200 secured card for 4 years. It's never over the limit. After a dozen threatening emails the last 3 months I get one today saying they closed my account for not sending my tax returns. For a $200 secured account!!! What the hell? I doubt I'll get my $200 back either. Madness.
@Anonymous, Welcome to the forum!
I don't mean to sound harsh, but you did have plenty of warning(s)
Always remember, it is their sand box, so it is their rules.