If you are looking for a private transfer pre or post cruise, this company looks like the best of the bunch. They are rated extremely high by reviewers, as well as have an A+ rating by the BBB.
You can submit an online quote request and should receive a quote quite quickly. In fact they were the quickest to respond out of all the companies I sent requests to. They have competitive rates, although they are not the cheapest in town. I personally liked the look of this company and for an extra 10-20 bucks, I think it's worth not worrying if they are going to show up or not.