Unprofessional and disappointed

I'm currently selling my car to we buy cars Ladysmith did an online application on their website corresponded with them via WhatsApp and they gave me an offer and when the buyer was supposed to come do a verification he's giving excuses for not coming to me to evaluate on the day we agreed on he has been very unprofessional and it's not the first time I'm dealing with him. On their advent the stat that they come to you but now he's disregarded the company statement. I called their call centre to see how to resolve the issue and they also put me on hold. I am so disappointed with about how this was handled.