Yes, it has happened to others so often that I have a lovely copy pasta that I used to help players :)
Some common reasons players have reported being suspended:
1. Failed transaction - insufficient funds, payment declined by bank or chargebacks.
2. Mismatch in Billing, Account, and/or PayPal address and name information. ALL the name and address information has to match.
3. Using the RMAH from outside the region registered to the account. For example, if you access the RMAH from Asia when you are registered at a US address it bans you.
4. Using the RMAH from a different country than the one you are registered too, even if within the same Region
5. Using the RMAH from a country where the game is not legally released (China) or where the RMAH is illegal (S. Korea). Playing from a country where the game is not allowed due to sanctions (Iran, Cuba, N. Korea, etc).
6. I have seen one report where updating the Mobile Authenticator resulted in a suspension. Player claims Bliz knows and it could be a bug. However with only one report so far I am taking it with a grain of salt.
7. False positives - they do happen. Sometimes the software catches something that seems problematic, but when reviewed by a human it is overturned.
8. Lately we have seen quite a few people playing on, and getting suspended on, accounts that are not in their name. Blizzard will only give the account back to the person whose name it is registered in. They do not allow account transfers.
To submit a ticket (required for most suspensions including Error 53):http://us.battle.net/support/en/article/diablo-iii-account-administration
How do I contact Account Administration?
Submit a ticket https://us.battle.net/support/en/ticket/submit and select Diablo III under the product section. Under the issue summary section input account administration or error 53 suspension if you are getting the error 53 message. Hit the continue to ticket creation button and select the topic:
If you really need to, you can call them to help sort out WHY you got suspended. Sometimes RMAH issues can be fixed on the phone. http://us.battle.net/support/en/article/contact
Some tips for calling:
1. The phone lines are always full these days (They support all of D3, WoW, and Starcraft). Spam re-dial immediately when you hear the queue full message until you get in queue and then stay there!
2. Cell phones hate being on hold and can disconnect. Use a land line (free in the US) or Skype (free to download and call them with anywhere in the world).
3. Be prepared for a 45 min + wait on hold
4. Be prepared to prove your identity by answering questions or giving Battle.net game keys
5. If you get it resolved on the phone, remember to cancel any tickets you have in the system to reduce the backlog there.