Actually had the very same conversation with my boss shortly after I joined my sportsbook.
My argument was that no bookie should be able to close somebodys account, as the losing gamblers will always outweight the winners, so why cant the books have a dose of their own medicine, and get beat at what they do best. After a heated debate, he told me that within a year my opinion will change, and I have to admit that he was right.
The bookies are there to run a business, and it is perfectly within their rights to close their accounts, to protect that business. However, I agree with DTB that they should do it with a little more tact, or their other option would be to employ you :shrug:
However, it is not hard to keep accounts with firms who close your accounts. Provided you have lots of friends, then it is easy to enough to get your bets on by using runners. These runners will normally be spotted, but as long as you have enough of them, then it is hard for the to track them down.
In my experience, closure after thirteen bets is a little premature, but if you are betting heavily then it is not unheard of. I would consider it as a private moral victory, but this is of no use if you cant bet that superb line they may be offering one week.
Who was the other book that shut you down??