This is my second year of being with DH and I have had very few problems with them. Their tech support has long wait times (especially on the weekends) because they could use some more people apparently. It can take around 32 hours to get a response (if you are lucky you only wait a few hours but on the weekend this is unlikely). Whenever I have had a problem and e-mailed tech support their answer was very straight-forward and helpful. You should get your refund back so long as you didn’t use paypal. But you should try and give them a chance to respond to your problem.
You’re the guy trying to install Joomla under php5 right? Instead of using the one-click install, have you tried installing it manually? Joomla does support php5 so you might not have any problems doing it manually. If you are going to be using a lot of scripts and such, it is a good idea to become really familiar with them instead of relying on fantastico or some other sort of automated process. That’s just my opinion, however.