Not sure if it is still the case, I had done costing a few years ago and found that Realex was more expensive than Worldpay for up to €30k of payment by CC per year.
At the time, if I remember well, Worldpay had a set up cost of £170, an annual cost of £100, 4% on all transactions, a remittance fee of about £10 per month, plus they were keeping the money for some weeks. This was based on a customer with AIB for realex and including the charges from the bank itself.
Bare in mind that this was a few years ago, the sterling was much stronger and charges might have changed. I guess contacting your bank would be the first step.
Also to consider, Realex is in Dublin if you need support....