@ Flor your words - "It's better for the company to use business visa because of the probationary period so if anyone fails during the period, easy to do and they did not waste their working visa".
Probationary period more or less is three months, so at the time that you were under this period you were still on business visa. That's not only improper that is also illegal. You were lucky for not being discovered by the Labor agents here. The penalty for that violation is deportation and possible life time ban here in Qatar.