An Dat Car Wash

Very unhappy customer. I took my Mercedes Benz there on Saturday 3rd of June 2017. They did a great job on my car for $15 outside wash! Now i just took my other car a Toyota Hilux there 4th of June 2017 and the board says for a 4wd outside wash $20.00. Now the wash attendant said he was unable to do the wash for that price because my mud flaps were to dirty.. Now i do not take my Toyota off road, i only use it to drive to work and back. So it was only dust that would of been off the road. I was unhappy as he was just trying to get more money out of me even though the board has a price on it. Would appreciate their feedback.