This seems remarkably odd because I have known scaffolders leave the scaffolding up long after the appointed time and the reason for that is that it means they don’t have to store it!
If it’s 12 week hire then it is 12 weeks.
You cannot physically stop him and trespass is a civil matter so your remedy would be an application to court for an injunction to stop him coming on your land.
I don’t know on what basis he wants more money if it was a 12 week period.
Quicker and easier is to pay the extra couple of weeks money under duress/mistake and then at the end of the 12 weeks, taking to the Small Claims Court to get the money back from him.
Much more straightforward than an application for an injunction to prevent him coming on the land although the application for injunction, you should get the legal costs back the legal costs are going to be far more than a Small Claims Court application.
2 ways of doing it, entirely up to you which you prefer.
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