Do t let them touch tour car, they will make an issue

Today I had a viewing by Reamohetse in Sandton, him and a colleague came. I gave them my car to look at and when they confirmed they were done he stated everything was great and I'll have the value by close of business on WhatsApp. I got into my car when leaving work and as I started my car an engine light came on, this was not there prior to the arrival as when he said he was on his way I went to make sure all was in order, my car has been assessed twice before and both can confirm that wasn't there and I have proof of it as I took a photo. I advise the buyer and he goes to Say it was already there which is bull, and at this point was 16:30 and still no offer as I think his well aware what he did. I asked him repeated for him manager to call me and my request went without worry. I called the main office line and they directed me through to his manager who confirmed his fet hing his kids and when his home he will investigate and contact me immediately. Which again was not done. I went through camera footage and you can see the college he was with was sitting with a diagnostic machine on my car. Why do you need that when assessing a car, We buy cars never did that. My car needs to go as I need to get my new car and now they have messed it up.my car was in good order and no issues with engine, electronics anything. This issue better be resolved or I will take this further. This is the worst service ever. Don't let them touch your car they will make proble.s that does exist.