jackson hewitt ripped me off on price for doing my taxes lafayette Colorado

I went into walmart in lafayette co to have my taxes done by jackson hewlitt. I was told it was quick and fair. The income tax rep asked me "how much did I usually pay to have my taxes done" and I said " 75-100.oo. He said "ok" and did my taxes. It took him five minutes as I only had to have them done because I have two rental properties. My soc sec is not taxed and I only do the rentals which is on a form. After he was done he then told me " i owed him " 287.00". I was really angry and told him so. He then made a call and asked someone about lowering the charge to me and evidently they said " no". My point is tell the person the cost to do taxes and stick with the same price not wait until after the taxes are done. I feel they should refund some of my money they owe me.