@motorhead446,
They are crooks, always have been and always will be.
The $4992 is way too much but, if you that have in writing, I suggest you do everything you can to shame them into a refund or sue them for the difference.
Last winter I helped a woman get a full refund and them to remove her 'system' by having her to go to Lowe's or Home Depot, that's where she signed up for them to contact her, and raising enough hell that the store manger and his supervisor helped convince them to remove it. It took her like 6-8 weeks.