UC and LHA

Hi @Jamesd49. Unfortunately without PIP there's not a lot else you can do. If you were in receipt of PIP you would be entitled to a higher LHA rate (1 bedroom instead of the shared room rate) which may give you more flexibility to move.
The usual suggestion is for someone to claim a DHP but you've already done this. 

Universal Credit unfortunately won't cover your entire rent because your bills are included in it. The housing element will not cover household bills, that's what the standard allowance is for. 

The only option would be to speak to your local council @Jamesd49 and ask for them to explain the reasons it has been decreased and see if you can change their mind. They are only every intended as a short-term measure.
PIP really is your best option in terms of increasing your housing allowance.