One of my accounts got banned 6 days ago – it got suspended due to "suspicious activity". Fact is, i did not use any tools to grow my profile, I guess they didn't like the fact that I got many followers soon.
If you have problems with a suspended account be sure to write
del@twitter.com. She's really helpful and will get you out of trouble (if you made only spam accounts she won't help you though).
Del responded to my request almost immediately, all other support requests did not get answered.