6 seater taxis?

[hillsgal]

Some of my family and I are going from Sheffield to a wedding in Chesterfield next weekend and I want to get a taxi for time and convenience, but there'll be 5 or possibly 6 of us. I've tried a few taxi firms to try and book one in advance, but they've all said they can't book a 5 or 6 seater for certain, we might get a 6 seater or we might get 2 normal taxis which wouldn't work for us as it will be me on my own with kids/teenagers so I don't want to send any of them off on their own. Does anyone know a company where you can book aa 5 or 6 seater taxi and definitely get one?

Edited October 10, 2015 by hillsgal