If it is a contract, then renegotiate your hourly rate, and make sure the evening/night shift hours are at double time. He can't change the contract in midstream as far as I am aware from a legal point of view. If you don't get more money, then see if you can accidentally slip on a wet floor... make sure you scream in pain from the top of your voice.

Make sure you know EXACTLY what your contract says.

I worked for a company with a contract that said something like 'normal/expected hours of working are 37.5 per week but you may need to work longer hours when the job requires it'.
In other words the 'hours per week' was pretty meaningless, and in reality I worked a lot more than that including many weekends.

As far as I remember from the days when I was a manager and had to look at the staff contracts, the company cannot change the contract in midstream without compensating you.
Have a look at www.acas.org.uk/index.aspx?articleid=3971

Generally, after the contracting part is sorted I'd go with the flow.

The guy's new and will find out.

Why work double your hours for no money - especially if you don't like what you are doing - let alone hate it ?!
Certainly stop the extra hours right now. 

There's something better out there. Just got to find it. Use those extra hours at home to do so

It's years now since I was a volunteer CAB Adviser, but if you enter a job where 'everyone' routinely works extra unpaid hours, it sort-of becomes an unofficial part of the contract I remember, even if it's not stated in black and white...

For general advice, the CAB site 'adviceguide.org' may be able to offer something and the CAB itself has a huge database to draw on - online and books aplenty - should you need to go that far.

Good luck Andr'e and hope you can get yourself sorted. I'm at the other extreme - I want more work than I'm currently being given...

Can i just say im not working the extra hours free gratis, They were just rota up every month. Like i say im not complaining but i was hoping the contract could be altered seen as id worked twice the contracted hours from the ofsett of my job. I do want the extra hours & more, i will work like a bull if need be im like that, but its whats going to happen now where the hours get sliced which renders the job not worth going to..

Also my experience, infact the simple matter of handing my resignation letter to my manager before I finished the job had in itself a massive pressure relieving impact on me. I felt like I was floating in air.

André, you need to explore the facts. Why is your new manager scaling back the hours? Is the company subject of the EU Working Time Directive or has it (I believe some private companies can) signed out of the WTD? If the new approach from your manager is going to prevent you from earning the money you need/want and assuming he is successful in his intention, it's time to look for a new job that meets your needs. However, if as you suggest, you are currently indispensable for the company needs, your manager will quickly realise his plan may not be fruitful and may have to change his approach. Having said that, remember the very true adage that, despite what might appear to be the case, no-one who is employed is actually indispensable. Everyone is replaceable. I hope you get it sorted out.