Cutting my pay but not my hours on return from mat leave. Is this legal?

[rightsaidfred]

I would be really grateful for some advice.
Briefly- my work is divided in to day and night work and I receive seperate pay components for this on my payslip.
I returned from mat leave working 3 days instead of 5 days and my day pay has been cut to 3/5 accordingly (I don't dispute this)
My night work- I still work the same as I did previously and the same as my full time colleagues. However my pay has also been cut to 3/5 of previous. None of my colleagues have had a pay cut.
Can they do this? Is it legal?
I haven't received a new contract and HR refuse to rectify this- insisting I am being paid correctly and have now stopped communicating with me!

doesnt sound right.Needs a new contract as well.

Yes, I would never have agreed to this and would have refused to sign a contract. It is so slow moving (HR taking over a month to reply to my initial emails about this that I worry they will try to say I have accepted the new terms by working them for three months

Definitely doesn't sound right.

Contact ACAS...they'll be able to help.

I'm not entirely clear what you mean, but if you are saying that your pay has been reduced by more than your hours have, then no they can't do that. Assuming you are doing the same job, your hours and pay should be reduced by the same proportion. Have you spoken to your line manager about it, or just HR? I would recommend dealing with your line manager and getting him/her to support you and hassle HR to get it right.

I would suggest you write to your boss and copy HR, confirming that your hours used to be X and your pay used to be X. Your hours have been reduced to X which means your pay should be X. Show your calculations. Request confirmation in writing of your new pay and hours and assurances that any mistakes already made in your pay amounts will be rectified with immmediate effect.

Thank you all for replying.
My line manager for my night work isn't clear as I am in a rotating post as part as a training programme during the day (rotate once a year) There is a kind of manager who oversees the whole rotation and she is aware of the suituation and has already written on my behalf. However she recieved a reply stating that I would not be paid. I have been advised to write to the training director as my next step.
I am not sure there is anywhere else I can go with this internally
Just to clarify- I am performing identical duties and hours to my colleagues and my pre pregnancy self but am now being paid 40% less.
To me it seems perfectly clear that this is unfair and I cannot understand why ir is so difficult to sort out.
I will speak to Acas tomorrow- didn't feel comfortable doing it from work.
HR are now not responding to my emails and I am finding all this very stressful. To make matters worse I am pregnant again and don't want to inform work until after this is sorted- and of course if my pay isn't corrected soon I will get my next maternity pay at the lower rate