I bought a brand new EV in March 2022. In February it developed a fault with the main battery. It is currently at the dealership, they have told me today that it needs a new battery and this can only be done at a specialised garage about 90 minutes away so it will be transferred there next week. I have been advised that once it is there there will be no updates to either myself or the dealership until it is ready to come back. They cannot even tell me how long it will be there but it will be at least 6 weeks. They can’t even tell me if they have a battery in stock 
I currently have a lower spec courtesy car from Enterprise. I have asked for a more equivalent car from the dealer now that this looks like being a long term loan. The courtesy car also has a £500 excess so I am terrified of damaging it!
Given that my car could be out of my hands for a significant amount of time, what are my rights regarding rejecting the car and asking for a like for like replacement? I have no issue with giving them a chance to repair the problem but the timescales are not reasonable in my opinion.
Thank you