Over promise under False pretences

I called up Aerea Connect spoke to I think a joseph from the Midrand and surrounding area. I was quoted an installation price to connect an Explora decoder and a second PVR price R650. When the guys arrived they basically just had to run cables of which was not discussed in the initial quote on my invoice its written 18metres was used changing the price by R600 rand. The amount of cable used was about right but if I wasn't quoted that one could have negotiated except the guy Joseph stuck to his figure or threatened to pull out the cables. These guys need to learn how to do a quote everyone know prices are subject to change but you need to either put it into writing or verbal agreement. Anyway I paid just to get rid of these guys ........I would never use their services again hope that they could learn from this as I did the hard way. Disappointed Customer never to return