I used Maks Car Rental which is based about 2 km south of Jomtien in Jomtien Second Road. They are run by farangs. No problems and everything went smoothly.
It is a little way outside Jomtien but I went there by motor bike taxi and got a friend to pick me up afterwards.
I assume they still operate but you will soon find out.
Recommended.
https://thai-rent-car.com/