As mentioned, if the fee was mentioned up front, it may be dificult to challenge it if the loan has now been drawn down.
I tried several years ago to get UB to waive the arrangement fee but to no avail.. However, their repayment rates were lower than others so the overall cost of borrowing was still less.
While AIB (and others) may not apply an arrangement fee, you may find that the cost of borrowing more than compensates them for not having one.
I got a car loan recently with BOI to upgrade my car and I was charged with a documentation fee of 63 euros. I think this is pretty standard with most lending insitutions. Even more previous borrower, a hire purchase company charged me pretty much the same.