Took advantage of elderly and overcharged.

I filled out an online form for installation and someone called me back to say they can replace my parents decoder with the new one we had purchased for R350. Later when i called my parents I was shocked to find that they were told to pay R1800. When I asked why so much my parents said that they were told the splitter they need is expensive but the installer will give them a discount, instead of R1600 he will sell them one for R1200. When I checked online it sells for R710. The splitter wasn't even new. They didn't give prices before the time just installed and gave the invoice after. When I confronted them about it all they said was that they have different suppliers so the prices are different. These guys prey on the elderly and people who don't know better.