Drain Cleaning San Francisco

I wish I could give them 0 stars. They came out to give me a "free estimate" and proceeded to work on my old leaking water heater by putting a hose on it, making me think this job had started. I had a couple other quotes from people for $1900 to do the work. The tech, Tung, told me it was a "shorty" water heater and would cost more money. I asked repeatedly for him to break out the cost of the parts/heater, the labor and tax but he never did. I signed for it because the work was done but then I saw that they put two sticks under my new water heater. I've called and asked them to explain their total charges at $2175 and they offered me a token $100 refund. Then they phoned me to call me a liar because I later signed the paperwork on the job, and reneged on the refund offer. I'm not sure how I can trust a business that a) started work without my permission, b) never broke out the cost of what I was paying for, c) never explained why they used two sticks below the heater and if that is their permanent solution to the problem. This heater is not rare, and costs $589 at Home Depot. All I want is an explanation and breakdown of costs that is honest.