Rejection of vehicle after failed repair UK

It's a long one. Bought a car on HP in September, engine management light came on on the way from picking it up. Told the dealer who arranged collection the following week. In that week it had numerous faults tyres, burning smell, faulty dash.. the list goes on. Car went in for repair (3 weeks). Got it back and within a few weeks all the previous problems started reappearing along with new ones. I told the dealer I wanted to reject the vehicle. He refused so I went to the finance company. They advised I needed to allow the dealer to inspect the vehicle. I did just that and emailed to tell them that I was authorising inspection only and no repairs! Didn't hear back for a while and so I looked into the original repair. The invoice the dealer sent me proving the work was from a business that had been dissolved 2 weeks prior. I requested the info of the garage my car was at now and they sent the report which showed the exact problems as before and stated work had been done. My finance people had given him until yesterday to lodge a reason as to why he won't refund and at the last minute the dealer/broker has requested another inspection as their is now nothing wrong with the car. I have pointed out that I didn't authorise repairs and that the inspection was only carried out due to their request. They are saying that they are going to refuse the 2nd inspection but the dealer is dragging his heels at every turn. I have been nearly 9 weeks without a car.

My question is... How long do I allow this to carry on for? (I don't have the funds to wait for ombudsman).

The finance have said I will need to wait for the dealer to be pay but this could take a while due to his previous delaying. He might try to over charge on milage and any damage (there is none).

Someone please help, I'm just going round in circles, I've already lost the APR rate that I got in September I don't want to lose any more.

Any advice would be great!