Access to carry out repairs

Maintenance

I am currently stuck in the middle of my contractor and tenant. Both accuse the other of being rude and the contractor is so upset that he refuses to start work until we have a three way meeting. The tenant says he's being stupid and expects him to start work on Monday, which he now tells me he can't do because he has arranged another job. Can I just tell the tenant that the contractor is coming to start work, provided I give notice. And if so how much notice should I give? I am really fed up with both of them and just want to get the work done!