My direct supervisor agreed to me working overtime for the whole of last week. However, the site manager has since stated that I will not be paid for this, is this legal???
Contrary to the previous answer, it would depend on what's in your contract of employment. Does this state that you'll be paid for overtime? If it does, then yes you should be paid. If it doesn't then it would be up to the employer. Many people don't get paid for the extra hours they work.