Working in South but paid in Sterling

Hi

I am Resident of Ireland and worked part time in Northern Ireland. I requested a transfer back home - Rep of Ireland but i am still being paid in Sterling.

I am on a part time contract which expires in July (it was June but my work keeps rolling it on)

I get £6.50 an hour which i believe is less than the Irish Min wage and also worried about my PRSI.

Any help would be much appreciated or which relevant body could assist.

Thank you