Premier Vehicle Sales

Me and my son recently purchased a car from the above dealer Phillip Knight on 17th February which was advertised on gumtree/Ebay as a classified ad. Based on the advert that stated that the car had recently been serviced, had full service history and described by the dealer we agreed a sale. After just over a week the car oil pressure warning light came on and was subsequently towed to a garage by the RAC, who believe the engine may need replacing! The RAC report is also attached.
We are awaiting an inspection by the garage and have also informed the dealer of the issues, under the right to buy off a dealer we are going to reject the car as it was not as described and under the Consumer Rights Act 2015 we feel our rights have been breached as the car was not as advertised.
eBay item number:
[protected]
So far the dealer has been co-operative but we will be looking to get our
money back so we can purchase another car. We paid £4k by bank transfer and gave a car in part exchange which was valued at £1k which we believe the delaer has now sold. Help and advice would be appreciated, before we consider any legal action should the need arise. My number is [protected] Abdul Rashid