LNB replacement

Dstv installers came to our house to attend to a fault on our DSTV. They found that the LNB was faulty and replaced it BUT they charged us R1950 for a 4 point LNB and when we checked on internet for prices we were disgusted to find that the prices veries between R450 to about R550. I would like to know WHY they overcharged us with about R1400???? On top of that we had to pay R450 call out fee AND R475 installation fee. We were ********** to say the least.