When I used LG Taxi service to the airport I always found them to be 100% reliable - merely booked at their kiosk o/s the hotel and it went in the "book" and sure enough they always turned up on time, in fact usually 10 or 15 mins too early.
As for Elmar - never again ! - booked a return trip from and to the airport - there was no prob on the outbound journey but they failed to pick us up on the return to the airport (when time is actually of the essence) - had to phone them several times and was at the point of merely getting a taxi (I had already pre paid with Elmar) when they finally arrived.
The excuse - a shrug of the shoulders and nothing else. To make matters worse there was another couple on the bus who told us they had been picked up in LG to go to the airport and their driver received a call when they were half way to the airport telling him to turn around and go back to LG to pick us up - they were not pleased.
Just to add to the inconvenience one of the other passengers was sick on the journey and the Elmar bus had to pull over for a few minutes so she could - well you know what !! We arrived at the airport just in time to check in.
I admit that was a few years ago now but I vowed I would never use them again - and I haven't.
I always hire a car for both the trip out and back to the airport, like to be in control of my own destiny