New Clothing exchange

I bought chino pants at this shop. Got home and washed it with other wash8ng. On taking it out of machine I saw it had a brown mark which look like an iron burn mark on it. I took it back same day I bought it. The shop assistant informed me it cant be exchanged as their chinos dont look like that. The MD said they will not exchange it. That was after I left as they informed me they will call me when MD call them. They kept the burnt pants so I paid them R650 for nothing. Thats the worst service I experienced ever. At least the MD could speak to me. Its my word against theirs and apparantly the customer.is not always right in their book.