I think my bank account has been hacked

So like the title says I think my bank account has been hacked. Some days ago I saw that a transaction was pending but I thought it was a mistake and did nothing. Now, some days later I realize that my account was used to make a purchase in Asmodee UK, that was 1,15€ (about 1£), and I was charged international fees too. I’m super confused as I do not know what happened and what I need to do now, please help!