I am just back from Jeju and I engaged Mr Lee Hong Min service on 8th March.
We have 3 adults and 1 young children (2 years old) with us during the 1 day tour.
First of all, Mr Lee speaks quite good English. He is always very prompt in his whatsapp reply.
He initially recommend the East course, but because we wanted to go hello kitty land, therefore we took the west course and also the west course route is nearer to each other.
Mr Lee was very punctual, and during out trip our camera "die" on us :( He just took out his HP and took many pics for us and after the tour, he whatsapp me all the pictures. Also he took us to a very delicious seafood lunch (with abalone and its so cheap) and we were very pleased to get good rates for the meal and all the entrance fees.
I would recommend him for your trip if you need any taxi tour service. his mobile +82 10-9396-4498.
He even give me a follow up to ensure we are back safely back to seoul. Very nice and caring tour cum taxi guide.