Rejecting Car on Finance

Hello, in September 2014 I purchased an approved used car on PCP over a 3.5 year contact.
The car was only 7 months old when I bought it so I was hoping for worry free motoring however it has been a nightmare.

Long story short, I've had serious problems with the clutch/gear box of the car and had it back at the dealership on eleven different occasions before I was finally given a new clutch (after I point blank refused to take it home as I knew there was an issue). To this day the car still has bother going into first and reverse, but I'm always told there's nothing wrong with it. I've also had the car back in the garage for more minor things like parking sensors, boot lock etc but I'd be here all day if I listed all the little things.

A few weeks ago I found the passenger door rusting and the manufacturer agreed it was a defect and paid to have it painted, the car is now waiting for the drivers door to be painted as it has rusted also. I went to drive it to work yesterday and a coil spring snapped. Its just problem after problem, I no sooner have one issue sorted till another one develops. I feel like for a 3 year old car its had quite a lot of problems, do I have any grounds to reject it and hand it back to the finance company?

The customer service I've received from both the manufacturer and the dealership I bought it from has been nothing short of appalling. I was actually told the issue with the clutch was 'in my head' however when they eventually pulled the car apart they realised the release bearing was faulty and there was an issue.

I'm paying money each month for a car that I'm not satisfied with and don't feel like its of satisfactory quality for the age and mileage.

Any advice would be greatly appreciated as I'm not due to hand the car back or exchange it until April 2018 and I really don't want to keep it until then.