Sadly this is a clear breach of the bonus terms, which actually read as line bets must be under 0.50 and single game stakes under 4euro. I agree that 'equal to' shouldn't be there, they should simply state 'limit is 0.50 a line or 4euro per single game' for the purposes of clarity. In this case the OP was clearly in ignorance of this term and placed wagers well over i.e. 5euro. So the casino has not resorted to any scummery here, simpy applied their terms. He has the deposit back, as again which is what the terms state when they say 'amounts in excess of xxx will be removed'.
FYI a 500euro cap on winnings/conversion to cash for bonuses is very common nowadays, especially since establishing the UK rules that the cash balance can be withdrawn at any time, along with winnings and effectively the bonus is separate therefore a 'second chance' free shot at some cash. It's thus far more likely statistically the depositor will make a withdrawal than under the old (mainly EV-) system of lumping the funds together with a combined wargering requirement of say 35-40x which would mean the player having to turn over thousands on games that effectively cost them 4% a spin, with the outcome usually a loss. So you cannot blame the casinos for capping this free shot.
To put it in practical terms, you get lucky right off on your cash, you withdraw plus any profits if applicable and forfeit the bonus. You have a crap run on your cash, with the undulating results of many slots and games it's not unfeasible that by the time you start playing the bonus funds that your returns start improving, or you hit a decent win which makes the bonus coversion almost certain. The players cannot (despite their wishes!) have their cake and eat it so to speak. It's why there's caps on these type of bonus arrangements and how the casinos stay in business.
Judging by the OP he's in the RoI not the UK part so was playing in euros. I don't know if this particular casino applies the UK-type of bonus rules or the old combined wagering ones. If the latter, then I agree 500euro isn't generous by any means.
