American Laundry cheated me the change

I went to Supreme Clean laundry in Drumcondra area. But that one had a Muslim woman working and I though the location might have the dog shit or some kinds of the Islamic voodoo going on to make the location not clean but like on the sand for the dirty living way.

So, I went to American Laundry which I used to visit during my stay in Dublin around September 2016. But this time, the clerk cheated me for the change. I paid a 20€ banknote and 50cent for 8.50€ laundry fee. And the guy returned only 4 of 50 cents to make it as only 2€. And when I asked about the change, he tried to give me 5€ note but he asked me if I have 10€ banknote or something also. So, we exchanged the money; he returned my 20€ banknote and I gave coins I grabbed in my hand. I had 5 banknote in my wallet and I paid the exact money to him. But, he tried to cheat me to get extra 10€! That was a double price of the laundry! So, I contact police for the cheating!