I had to make a return at Canadian Tire. Anyone who has done this before knows it can be a scary experience. I have witnessed many disgruntled customers (not that I would ever be one!). Lucky for me I had my receipt and an unopened package!
Waiting in line, I notice that there is a sign posted for waiting customers to read. It was related to Health and Safety in the workplace. Coming from an OT and OH&S background, I assumed it was just notifying the public that they adhere to OH&S regulations, yada yada yada. However the gist of it was actually that healthy workplace includes their non physical environment including interaction with customers and they will are not to tolerate harassment and abuse from customers.
If you need a statement to the public in the Customer Service line that employees will not tolerate verbal abuse such as threats, yelling and profanities, perhaps you need to look at your return policies.
Just a thought.