How to handle a contractor mistake

[Nat C.]

Guys, please help me out with your opinion.

I ordered tiles and had them delivered to the property.

I specifically told the contractor in writing, what tiles were to go on the bathroom floor and walls.

Today he sent me pictures of the tiled bathroom. I was shocked when I saw that he has used random tiles, not the ones I had instructed. By random, I mean I didn’t even buy these tiles, so I don’t know where they came from. He just found some tiles laying around the property and put those up. But because there weren’t enough of them, he then used another tile, so there are 2 types of floor tile, which looks atrocious. They are also beige, a colour I think is woeful, whilst the rest of the colour scheme through the house is white and grey.

I’ve asked him to remove and redo it and he’s not happy and won’t redo it. I don’t know how to resolve this situation.