Bad at pre - booked airport collectiontaxi service

I'm very pleased with sport taxis service travelling to the airport. However, I'd strongly advise not booking a taxi with sport for a taxi back from the airport. I've done so twice. Even though they ask for your flight number, on both occasions, nobody was waiting for me after I landed. The first time, I went to sports stall at the airport, had to wait and eventually got home an hour later than I should have. Tonight, the same thing happened again, but this time there was a long queue even though I booked. The metered taxis outside the airport is a better bet than booking with sport. Learnt my lesson, Will never book airport taxis with them again.