Six months without any updates? How is this at all acceptable? Please explain how you can go 6 months without updating your financial backers AT ALL.
There is not a single acceptable reason for this. Not one. A 5 minute call to someone who can update the website would completely remove any angst or apprehension your backers have.
I will NOT request a refund because at this point, why let anyone off the hook. Produce what you said you would produce. It's already clearly taken longer than anticipated which would have been fine had there been regular communication.