Email is best but you need patience. I've gotten many RHPs from them over the years and to be honest I wouldn't get an RHP from anyone else. They are just drowning in orders these days - as is true for PVC enclosure makers. I think reptiles are increasing in popularity and also a LOT of people got them during lockdown.
I won't make excuses for Bob (the owner of ProProducts) but I do know that he is the person reading and responding to every email and responding to every call. Hang in there and just know that the quality of these products is worth a little bit of hassle, at least IMO.
In the meantime, it's very possible that folks here can also help answer some of your questions!
Editing to add that I am in the process of ordering a new RHP from them and I'd say it took 7-10 days for them to respond to my email answering the questions that help them determine what size RHP to get.