I posted early on in this thread and have read through the rest, I agree with what everyone has said. That being said I personally think it is always best to be certified locally. It does several things for you. First you are generally trained in more difficult conditions than where you tend to vacation, by that I mean it is typically lower visibility and quite possibly colder. I dive where if we get 10 ft of visibility we think we have a great day. I have heard stories of carribean divers where the visibility suddently drops to 20 ft and they completely freak out. I also hear about carribean divers complaining about 60 ft of visibility, are you freekin kidding me? The second advantage comes in that you are not going to always be able to dive in Carribean waters and if you want to keep up your dive skills you need to be able to dive in your local conditions. I have not looked at where you are but am keeping this statement general so that it can be of use to more than just yourself.
That being said I really think you should certify locally. It will also allow yourself to really enjoy your dive vacation without having to spend two days or more doing cert dives. You're doing this to go enjoy the ocean so lets try to maximize that time. I get the distinct impression that you no longer want anything to do with the previous dive shop you have dealt with, that's fine and I have no problem with that. That being said I think you should seek out a local instructor/dive shop that is willing to work with you. You already have the benefit of going through some training so unlike most other new divers you now know some questions that should be asked before you start training. You need to find yourself another shop or instructor (and that other instructor may very well be with the shop you are already taking your lessons through) and ask them how they handle divers who have problems clearing, or what if they have problems equalizing, or what if whatever else you come up with. I think you get the picture here and I will leave it at that.