Is it possible to bend the law?

My sister started renting her flat with three other people less than a year ago and it has turned out really badly cause they have all fallen out. In their rental agreement they can’t leave the flat before their break close without losing their deposit. And the break close is in November so it is ages away. And neither of them are going to leave the others to have to pay extra for their room because they still care about each other.
So if they want to leave they have to organise new tennants to replace their rooms.

However, no one wants to rent their rooms because for the area it is quite expensive for what it is. They are all really unhappy in their flat and id really like to help them out but don’t know anything about law.
Or if there isn’t anything in the law that they can do what are the best ways to advertise a room
For rental?