Damaged carpet after cleaning

We handed in an expensive carpet for cleaning. The carpet has more than two colors in it. We were advised that they test first on the darkest color to see if the liquid will stain or run. If it does not show any running effect then they will go ahead to clean the carpet. when we went to collect the carpet it was damaged with stains. We asked around what to do now and was abruptly told to take it to another cleaning company. the issue is the damage is done. Not sure how to go about the matter now as the owners are not willing to compensate for the damage. The carpet is still with them.