I did not place a pre-order through the IndieGoGo campaign but ordered directly from the MRG website in April and paid using PayPal.
Fortunately, the order is still within PayPal's 180-day "dispute" period. Today I filed a dispute with PayPal. I also emailed a request for a refund from MRG. Per PayPal, I "have 20 days from the date you opened the dispute to resolve it with your seller. If your seller isn't responding or you can't come to a resolution, you can escalate the dispute to a claim."
If, as I expect I don't hear anything from MRG, and if after the 20 day period it is not resolved or there has been no communication, then the dispute will be elevated to a "claim."
I'll let you know if there is any response.