I want to get a good, used Mercedes-Benz B-Class diesel around 6-7 years old. On a test drive, everything was good. Only that the car's sat nav screen doesn't work and the seller didn't know about it. They said they will fix it. Should I worry about this issue in a long term? Can I ask fo the lower price? I want to get a car for things like going for a grocery shopping, dropping the kids off at school etc and I've found searching for a used car exhausting. There are so limited options out there. I want to wait but I also don't know if I will find a car like this one again. Thank you in advance.