This is the first time I post in one of these forums but today I'm very happy I can express my experiencea.
I ended up in OK Car Rental because it was close to my hotel and the came, picked me up and drove me to the shop. I'm not going to insist on the fact that the ATV that I rented was in a real bad state. The lights didn't light the road, the tank guage did not work at all, same as the Speedmeter, brakes were dangerous and so on. When I raised all this I was told it's difficult to keep them in perfect conditions on an island (last week I was in santorini and I renter another s wheeler and everything was just great).
Not to make it a long story, the three keys were attached by two key rings, the main and one more that was just a piece of wire.
I drove the first day and for some reason I lost the key for the key for the box/trunk flew away and I lost it. When I returned I told them that I had lost the key and then the manager told me I had to pay 10 euros for a new key. I know 10 euros is not a lot, and I know I could have paid for the new key but i didn't want to pay for it as I knew it was not my fault. We started an argument and the manager stared to raise the tone of his voice. Eventually he said he would chop my head off, literally. My wife got really scared and so did I; he shout at me and told me to go away the he had my card and he would charge what he wanted.
It was the only bad experience on Mykonos Island, and that's why I suggest NOT to rent from OK Car Rental. If you do so, get ready to face this kind of treatment. Apparently another person had a similar experience with the manager some time ago, you can google OK Car rental Mykonos and will find it.