Email them your schedule and they have someone waiting - also provide contact numbers for the day. Today I got a call roughly 2 hrs before my flight to check what time i would be arriving at the airport and there wasa guy standing there with a visible placard with my name on it waiting.
They have been going for over 18 months, how long exactly I dont know. I was recommended them by a Bangkok based colleague who has used them with a high degree of satisfaction over that period.
They have various options, for 20k you get the buggy pick-up as well.