Still owed money from my last job?

This might not be the place for this question but I'm at a loss atm

Quit this job back in November, small little local owned shop as I was moving towns.

I still haven't got my holiday pay from my boss

Its like 600 euro and he keeps making excuses about the business failing - and how I didn't tell him in advance my plans to leave (I did) so he was surprised he had to pay this amount

I'm just wondering does anyone know who I could even contact about this, I'm sick of chasing this man x

Thanks a mil