Lying 'mistake'

Sent my staff to get a quote and was quoted R785 for Dunlops - went to fit the tyres and the price was almost R900 - when we enquired, we were told that the salesperson, Eugene, had made a mistake. He quoted on 14" instead of 15" which the bakkie needed. Doubt it was a mistake (or the salesperson is an idiot) as Eugene came to the bakkie to check the tyre size. So now you have the little option as they removed the tyres from the rims, and are ready to put new tyres. What a ripoff! And the supervisor Rauff is off for the day so there's no one you can talk to.