Car service in Portland/Dorset

I'm looking for a car service that will take 6 of us from Portland/Dorset to Highclere Castle on September 2, 2014 (Brilliance of the Seas) Any recommendations for a car service. I had planned to use Here 2 There car service, but they just informed me this morning that they don't take credit cards!! UGH Any help would be appreciated!

Can you not rustle up some cash between you all? From an ATM?

Yes we can, I'd just like to prepay it now. Before we get there.

There's a few operators on this thread:

http://boards.cruisecritic.com/showthread.php?t=2058366&highlight=portland

But, like the others say, if you're happy with your quote I'd be inclined to get cash from an ATM.

And it has the advantage that if you have to cancel for any reason there's no penalty.

JB :)