Audi A1 2015 endless mechanical issues since the day I bought it : deal cancellation

I have bought an Audi A1 from Webuycars with a Gold sticker that mentioned the Vihecle has no issue at all. First month of buying the car it had gearbox issue and they persisted on fixing the car and not offer to swap or exchange.

I went back to them and mentioned the car it still has issues they now say 6 month has passed.

@Webuycars I have been complaining about this car since the first week of purchasing it, emails are the, calls are there to prove that all I wanted was a cancellation.

I don’t have joy or peace in driving this car as it was endless issue and I still want to cancel or swap the car. Please kindly assist