Yes, if you have cancelled the car it is no longer showing for sale on eBay. If they have sent you a mobile number After the car was cancelled this could be seen as the beginning of an off eBay sale, so the car Must be listed on eBay again.
Call them back say the car has to be relisted on eBay for them to purchase the item again.
You could add that cancelling you had to pay the non refundable listing fee ( it is still I think £14.99 for auction / Buy it Now listings, and b£19.99 if sold in a Classified ad format), you will pay this again for the relist.
If they do not agree, I would not sell them the car after you cancelled the sale on eBay.
Be aware, there is no protection when selling a car on eBay, but after purchase and inspection, the buyer must pay only cash or bank transfer when collecting the car.
@jolly_sivell