Employment rights in Ireland ( full time employee who is working weekend seeking advice) pleaseeeee help!!?

[Nicola]

Hi,
I am hoping someone can help me please.
I have been working for an family entertainment center for the past 5 months , I worked behind the scenes getting the center ready to be opened to the public for the first week of employment (brand new center) .We then opened to the public and they hired all the staff needed ,
within a week a got made to supervisor and my pay was increased, around a Month later I was told they were putting me on salary in doing this i noticed my pay was cut by 50 cents an hour I said this to my manager and she told me ''that's just the way it works out'' I was fuming but after 3 unsuccessful attempts to correct this and being passed around to different people i left it.have been roistered on every weekend since I started, I didn't mind this at first as people were trying to find there feet and they need strong staff etc... but I am now 5 months in and getting pretty fed up as My colleague ( im her supervisor and we started same time) has had every weekend off since we started and has only been roistered 9-6 mon to fri ( would love these hours) and has only had to work 1 Saturday since she started, she has no agreement with our boss to work these hours she just keeps getting roistered them which i find is VERY UNFAIR as Im working every weekend for no extra money as i found out she has been put on the same salary as me. so I am working horrible hours ie until 10pm most nights during the week and full time weekends and Im a supervisor yet my colleague is working mon-fri 9-6 on the same pay!!! my boss is quite unapproachable but i need to resolve this asap so I need to know my rights and entitlements. I was told weeks ago by my boss that '' she is no good at the weekend'' ( our busiest times) but yet she is on same pay as me so whats my benefit for giving all my weekends up?.
also must add, we have a review system in work through social media and website and they have been inundated with excellent reviews on me so why do i feel like im being punished for something? can someone please offer some advice .
thanks for your time.

[BILL]

If your boss won't listen to you, then there isn't much you can do other that quit or accept the job the way it is. Good Luck