Hi Rickybinnie and welcome to GoY. I'm sorry to hear workmen managed to damage you acer, I trust you are seeking compensation. Provided your acer is in the ground frost should not be a problem, if it is in a pot you might want to wrap this in bubble wrap if the weather gets very cold to stop the pot freezing. If the branches have been completely broken off you will not achieve anything by reattaching them, just tidy up the break so that there is a neat clean cut at an angle.

Same advice from me Ricky. Get the Secateurs out and make the breaks clean and tidy.

You could put some antiseptic tree paste on the cuts to seal them - but as said by Pimpernel, make sure they're clean cuts.

Thanks for the advise. Much appreciated.

id cut them back to the first mane branch you come to and it will heal over and you wont know its been there after a while . ive found if you just cut them back to the break the rest of the branch dies back anyway .