A Good Neighbor Heating & Cooling

My furnace broke down again, and it's only been 4 years since A Good Neighbor Heating & Cooling installed it. I called them to fix it, and they ended up charging me a whopping $516 for a simple $9 part that took them just 20 minutes to replace. When I questioned the cost, they rudely called me stupid and claimed I didn't know anything. I expressed my concerns about their pricing, stating that they were taking advantage of people. Unfortunately, they didn't provide me with an itemized breakdown, just a total amount and told me to pay up. I ended up getting into an argument with the owner over the phone, and he even went as far as wishing my house would burn down. Their behavior was highly unprofessional, and I strongly believe they shouldn't be in business. It's worth mentioning that they offer a mobile service, but they still wanted to charge me for going to get the part.