Bad bad time managemt and poor communication

I took my car for a repair, on the 25. 06.2021 got it back and still the heater that was one of the problem that was suppose to be fixed it was still not working. The things that where meant to be fixed was over heating, heater, aircon clucth kit. However on the 28th. 06 2021 if m not mistaken with the date my car started to over heat again the heater not working mind you I paid all the money 13k immediately with no hesitation as I trusted them took my car back to them to ask them why is my car over heating again and they say it's the gasket and about the heater they not sure what causing it as a big repair workshop you don't know like really. And my problem is why was a gasket not picked up at first when they where checking why there's overheating and when I asked they like we not sure why and they quote me again 11k including labour which I don't know as it's still under warranty. Secondly they will never call you back unless you do follow up your self and thirdly even their manager quoted me on a wrong how I don't how do you do that a whole manager.. I'm so not satisfied at all. How do you check overheating of the car first and never see if it's the gasket or t op and again I spoke to Michelle one of their team and she said to me lucky I didn't blew the top and gasket I stopped when the car over heated that was smart and that was telephonically then they say they don't know why she said so and she has resigned and I don't have proof of it, how come a company can't track calls and see if I'm lying or not even have them dates on when I was talking to Michelle they can track our calls from there..