Bought a second hand car from a private dealer - what are my rights to reject the car?

EDIT: London/England

Hello

Looking to get some advice as I'm a bit lost and feel like the dealer is taking advantage of me. I am a new driver and don't know anything about cars.

Below is the timeline of buying a used 2012 Honda Civic from a private car dealer near Heathrow.

I traded in my Hyundai i10 for a 2012 Honda Civic (114,000 miles) and paid £1,550 difference and the car was advertised for £4,300 and was given a £150 discount so £4,150. The car started showing heavy signs of blue smoke from the exhaust and drinking oil like crazy.

Civic Timeline

  • 3rd May - payment (via Monzo bank trasnfer) and confirming I will pick up the car on 6th May
  • 6th May - pick up and documents signed
  • 11th May - called dealer to let him know about blue smoke from exhaust
  • 18th May - brought car to dealer for fixing blue smoke from the exhaust. They did a fresh oil change and changed spark plugs
  • 30th May - called dealership to say smoke not fixed, asked for options and solutions. They said they will get back to me
  • 1st June - oil top light on dash, 2 weeks away from the fresh oil change
  • 2nd June - topped up 750ml of oil
  • 3rd June - check oil level message on dashboard
  • 4th June - chased for solution from dealership, told he will get back to me next day. Told them about oil level light
  • 5th June - local garage inspection for second opinion. Added 1.5L of oil

The dealer has received two emails from me and never replied. Always speaking over the phone. Dealer offered to change the engine or pick a different car. I only want refund and they became defensive when asked for refund. They are now offering me £3,850 because of 'fair use' and a small scratch on the passenger door as I've been honest and transparent with them when asked if there is any damage to the car.

When I said I want to bring the car myself and leave it at the dealership, I asked for the money on the day. He said that he doesn't have the cash, I have to wait a few days as he needs to sell inventory for me to get my money. I asked for written confirmation for him saying he will provide refund and said will provide this to me tomorrow when I drop off the car.

So now I'm thinking, I'm dropping the car off to them, leave without money and a written statement. That was the last straw for me. I already invested the following amount in the car because I thought I will keep it. Now they are expecting for me to take the car to them, pay me £300 less and also leave without cash.

£200.72 - service Newton
£300 - tyres
£19.74 - wipers
£72 - joes garage
Total £592.46

What are my options considering the timeline? What is the best way to proceed?

Thanks