Help! Lost/Stolen Bank Details

Last night I was going out and could not find my wallet no matter where and how long I looked for. I have to come to the conclusion it's either lost or stolen. Even if I lost it e.g. dropped it on the street, it is likely someone appropriated it.

A lost/stolen wallet isn't such a big deal, there was about 50 euro in it, my bank cards and my packet of birth control. It's a pain but not the end of the world.

My main issue stems from the fact I had written out my sort code and account number and bank address on a piece of paper and jammed it in my wallet as I was intending on driving to the credit union to change the direct debit and needed those details. So there is a chance someone out there has my bank card, and therefore my name (signature is not on it), also my bank details.

What do I do? Do I need to open up a new account? Just tell my bank (ptsb) and let them keep an eye on suspicious transactions? How much damage can a person so with bank details as oppose to atm pin number - would it benefit them to set up a direct debit really? They would not have my home address. Please let me know your thoughts, I'm really kicking myself for losing my wallet with the double whammy of being an idiot and leaving my bank details in there.

I'm not having a good week.