Crown Crest Capital complaint: Buyout figure on Heat Pump

We were forced to agree to a monthly payment with above company in order to purchase our house (the previous owner (seller) somehow got involved with this company). We never received a copy of the contract or any other supporting documentation and had no knowledge of the terms. Since heat pumps installed new typically are between $5500 to $7500 (this heat pump was installed mid 2017) I thought no problem we will buy it out. The only time this company has replied is when I asked for buyout. The buyout was an astounding $11,445.95!!… for a used piece of equipment! The rental of the equipment sees no end until sometime after 10 years!!! Our lawyer sent them a letter and made numerous phone calls to try and find some resolution to this issue. They never replied. They are now calling every day pretty much as we have quit paying monthly payments. I am also being called by another company called Simply Green, these 2 companies are somehow affiliated although when asked about this during a phone call no one at Crown Crest Capital seems to know.