Read through the TER Instructions at the top here. Also keep in mind that most providers will have multiple ways to screen, not merely other provider references. That should be provided on their web site but if not you can text/email and ask if they have alternative. If they do they will let you know.

Another thing to consider is participation on your local board. If you're looking for providers that are reviewed here on TER then you might also find they are posting here at times. If you post to those forums they will get an idea of what you're like and might be more newbie friendly for you as opposed to just some unknown stranger you are now.