You probably gave your credit card details for a trial Real Music subscription. You get one email when you do it, and will hear nothing else thereafter, so if you're not checking your credit card statements, they'll keep billing your credit card. I'm embarrassed to say that I didn't spot it for 16 months, and they took £8.50 each and every month with the description "RN REALMUSIC 0870-2402486"
When I got it cancelled, the confirmation email was from firstname.lastname@example.org
I checked my old emails, and the only other email I had from that address was the same date they said the subscription was started at 03:45 am. I know from my diary that I was online at that time, so I probably gave my credit card details to view some music clip, intending to cancel right after, but then forgot.
If you don't have an Irish number to try, call the UK number 0870-2402486 to get it cancelled.