EXTREMELY POOR SERVICE

i bought Opel Corsa 1.4 Enjoy 2015 model on 28/08/2019 which started giving me problems on 06/09/2019. To date (18/12/2019) i have been stuck 5 times on the road. The car just stops in the middle of the road and not respond to the accelerator. The car has been taken twice to Williams Hunt Edenvale who have been unhelpful. They have failed to diagnose the problem & on top of that refused to give me a courtesy car after being promised by Tracey Nagel on my 1st visit to the dealer. On my 2nd visit it was the same story, they said they cant give me a courtesy car, i must get stuck on the road and then give them a call for them to come diagnose the car while it is still showing mechanic sign on dashboard. I did as advised today 18/12 they managed to diagnose the problem but didn't take the car with them. They promised to go investigate in their office and come back to me. When i do follow ups, i am being told stories of getting back to me next year. I must remain which the car that has a problem meaning i can travel