London Airport Cars..Return Transfer for six

I Found London Airport Cars on the internet. Having never used them before, I was satisfied. They provided a very reliable service, picking us up from our home and on our return journey, picking us up from the airport. There was plenty of space in the mini van, considering there was six of us with suitcases and hand luggage. The driver arrived on time and happily lifted the heavy cases both in and out of the van for us. The interior of the van could have been cleaned before picking us up though, as their was litter scattered on the floor, probably from a previous journey and the van was cold half of the journey.
The payment method for the service needs be improved and clarified. As when trying to pay online, it did not allow me to. I therefore assumed that i would have to pay by cash, but the driver was not fully aware what the price was, and i ended up paying an extra pound to what was quoted online. This happened on the journey out and on the return journey home. All in all, we were gratefull to have arrived on time for our flight and have them waiting for us on our return, but i would say that this was like using a local cab firm, but with mini buses.