try orange car rental or try car hire on some of the flight companies
http://www.holidayautos.co.uk/car-hire/dalamanairport.htm
http://www.hotelcypriot.com/rac.htm
https://www.oludenizbeach.com/(S(1efxr2vuavbytazgr4mztb45))/carhire_turkey.aspx

We use http://www.carjet.co.uk and have always found them to be competitively priced and reliable. We hired a car in Tuscany last year and have booked with them again for 14 days hire in August for Dalaman. You can book online (or over the phone as they have a UK-based call centre) and receive a voucher at the time of booking but don't have to pay until you collect the vehicle.

THANKS BOTH VERY MUCH....