thefrogs ~
I was also advised that they didn't need them at all as I had originally looked at hiring a car. Unsure if this is the standard with small children. But you can always ask that you are travelling in a vehicle that has seatbelts, ours with this company didnt!
We too used Hamish Mcturk for our transfers this year, and while our journey to resort was fine, our return journey wasnt. What was supposed to be a private transfer turned into a 2am jaunt, picking up a big family booking from another hotel, a change of drivers and a stop to refuel the mini bus. The driving left a LOT to be desired and while I have even been rally driving I have never felt as unsafe as what I did with my 7 year old son on our return to the airport. Make sure that your transfer is a private one of that is what you believe you are paying for . . .we did and we were so late getting to the aiport in the end that we were only 4 rows from the last of the flight being checked in!
Not only did I feel uncomfortable cos my son wasn't on his usual seat, there weren't seatbelts that worked in the minibus that we went on, but, I have to say, we will not use this company again!