Wrong, at least to the extent that you will cause yourself a lot of inconvenience for the sake of a few Baht. Thre is the law and then there are the regulations and then there is, as in other countries, the discretion of the individual officer if he has some suspicion about you.
The 'service fee' was asked for as a favour and there was no threat to deny passage. Argue with the guy if you want but it's not worth demanding to see the boss.