New boss gets us to work overtime, all weekend and till 9pm. Promising that we will get that time back.

We get the project through the door. His KPI looks great to his boss. He then slithers his way around hints about this time back. Someone confronted him today and he says he can't officially recognise the over time due to company policy. The fucker.

Were the promises made in writing?

Yep :/ in online chats

I mean you could "work" but not work, it's not pretty or ethical but it will defo prevent him doing anything similar again, especially as he will be held accountable. Unpopular opinion: I don't mean to be a "rebel" but if that's how you fix the world, by confronting the bullies. You could alternatively take it to the top boss and if he doesn't recognise it and doesn't reward you and accepts this kind of behaviour, you should find another company and give them shitty reviews from Glassdoor to Google.

Yer this involves 6 people. We are discussing what we can do about it and where to take things. It seems that his boss and that bosses boss is compeltly against over time and will not recognise it either. That boss had a boss who could pull the strings and used to stand for us but he's just left. Other than that it's shareholders etc I don't think they can do anything. We have a HR department in another county. Not sure what they can do.

In addition this isn't the first time this has happened but this happened with our last boss with verbal promises and asked to track our over time they then resigned. I got almost no work done today due to being so angry at this and unable to think straight.

If you don't get paid for the overtime, walk out.

If you can afford to do it, I agree with @Root 100%. Best to start looking for a company that will treat you better regardless because your company culture sounds pretty toxic if a boss is going to let someone get away with doing this to his/her employees.

Not to mention never working a second of overtime again

From my experience I have got fuck all back from working overtime. We had this one death march that went for weeks. Team members regularly worked at least 2 hours overtime each day and we got one day off. A single fucking day. Oh and a "thank you, the client was happy!". The client can fuck off. As far as I'm concerned I wasted hours I could have spent with my partner and friends.
Every company has a different culture but if overtime is regularly occuring then something is wrong with the process / client expectations.
I learnt pretty quickly from this to say NO to overtime.

After a long meeting with all developers it's been resolved. There was a heated discussion but it was addressed today. Time will be given back as promised. It shouldn't have come down to the chaos it did. But management is now holding up their side on this occasion.