Jenkins Mitsubishi

My experience with Jenkins Mitsubishi went the exact opposite of how I thought it would go. I bought my car new from Jenkins Nissan in 2012. I have always had excellent service and treatment at Jenkins Nissan. I went to Jenkins Mitsubishi to look at a truck and get an estimate on my car's trade in value. I gave my keys to an employee to verify the miles and look over the car. The employee did not give me my keys back, but left them in an office across the building. He came back with a trade in offer of $2,000. A car Blue Booked between $5-7000. I told him that must be a joke to lose 90% of a car's value in 6 years. He said he could offer $2500-3000. I understand the sales process and didn't expect the full value, but that was less than I wanted to trade it. I did not want to look into trading my car in anymore since I am still looking for vehicles and not set on one in particular. I asked for my keys, and we went to get them. Instead of getting my keys, the employee got his manager to try to make another deal. I don't want to play games and be moved from person to person, I want my keys so I can leave. Is this normal for employees to hold customers keys in a different room and not give them back when they are finished being used? I gave my keys to the employee to look at my car, not detain me in order to waste my time playing games.