Absolutely horrendous experience. Visited with a f...

Absolutely horrendous experience. Visited with a friend a few weeks back to help him buy a certified pre-owned 2015 Civic. I believe the salesman's name was Andre Guerrier.
Firstly, the two cars we'd booked for test drives weren't there - one was apparently sold, the other gone for 'detailing.' This could have been mentioned when the appointment was confirmed, saving us the hassle of the visit.
We proceeded to identify a few other cars we may potentially be interested in. Throughout this process, the salesman took extremely long to verify what cars were present, and what they would cost. He also took a 15-20 min call in the middle, as well as another customer for half an hour, even though his priority should have been us.
Eventually he identified 6 possible cars which met our criteria. We were told they were present at the Huntington Honda West branch, so we drove there. He spent nearly an hour trying to find the cars - apparently none of them were there. We went back to the main branch, found a deal we liked in their inventory, and were assured the car was not present because it was gone for 'detailing due to a spilled drink' but would arrive in a couple of days. We put a deposit down, and finally confirmed the deal after spending >5 hours at the dealership.
When we checked the CarFax report a couple of days later (prior to making the full payment for the car), we saw that the mileage had jumped up from 10k to 20k in the space of a few days. After repeated calls and emails, we were initially told this may be an error, before being told that the car had been sold to someone else. At this point, we'd had enough, and went to collect the deposit (which also took >30 min for a 5 min process).

All in all:
- How do you double sell a car?
- How does a salesman not know which cars are present in the lot and which aren't?
- How inefficient do you have to be to take 5 hours to make a simple deal?
- Surely salesmanship 101 is to prioritize the customer in front of you before taking another and ignoring the first?

Would not recommend this dealership at all. In the end, we ended up finding a much better deal for a lower price from a private seller.