Has any use Yellow Taxi for a pre-booked transfer, www.yellowtaxis.es I have had some issues trying to book a transfer to the airport with a short stop before at the Sagrada Familia. Either the price was too high, they didn't have availibiliy or they didn't reply to my email. We need a van for 7.

Yellow Taxi's price seems reasonable and they can make a stop before the airport if we have time. Their price is 200euros with up to a 2 hour city tour beforehand.
Their email:
The price from Barcelona Centre to Airport for 7 persons and two hours on tour will cost 200€. This price includes all supplements, baggage, etc.