If you know of a grooming facility that is not working with animals in a humane fashion, document everything, including a description of the incident(s) itself, who you have spoken to regarding the situation, as well as dates and times.
Report the incident.
Report the incident(s) to several sources, like the National Dog Groomers Association of America and the local chapter of the Better Business Bureau or your state's consumer protection division.
Keep veterinary records.
If you take your dog to a veterinarian as a result of the injury, obtain the medical records from the vet hospital and a letter from the vet stating their opinion of the cause. You will need these records if you intend to be reimbursed for the medical attention for the injury.
Check to see if it's animal cruelty.
If your complaint deals with animal abuse, contact your local animal control agency to see if any animal cruelty laws have been broken.