mounting and balancing

This wasn't my first time there!!! This is the straw that broke the camels back!!!! So I brought my new tires and my rims in for mounting and balancing. I told them I purchased tires elsewhere from the beginning. They never told me they charged more for not buying tires through them. Gave them my tires and rims!! Went back the next day to pick them up and they tell me they charged me more then normal because I bought the tires on line. them she tells me but that's okay because I saved so much more on line then they can sell them. I'll never go there again!!!!!