Online Selling whatsapp

Drove all the way from the west coast to parow mall on Sunday for nothing -+2hours drive...R500 petrol wasted. I was looking to sell my laptop and decided to opt for the cash crusaders online selling using their whatsapp number they asked me all relevant questions in the chat and gave me an offer which was acceptable to me. They also asked for my Specs on whatsappp of which I provided . I then let them know that I will be coming in today to sell the laptop, I drove from Saldanha Bay to Cape Town just to sell the laptop as we no Cash crusaders in our area they moved we don't know where to..when I got there was asked the specs of my laptop that's it nothing else and I was offered less a quarter of the offered amount from whatsapp..they didnt even check anything on my laptop. It's like a **** to let ppl sell their items for next to thing. On whatsapp a different story face to face another story. Be clear with the people. The guy who helped couldn't even say anything after I told him what happened, he rather said I should just go to complain. **** ring.