[Alec Brandon]

I work in a call centre, I am the Quality Manager.
You know when you call a 800 number and it says 'This call may be monitor for quality purposes...' well I manage the team that listens to those calls.
I say this because I know customer service.

I'm sorry to hear about your bad experience.
Her are some key things to say when dealing with these issue (I recently had a bad experience with Canadian Tire myself).

Tell them... in a VERY calm, friendly, cooperative tone...
I am very dissatisfied with the service because (always give a reason!)
I understand how important customer satisfaction is to Company Name and want to provide every opportunity for you to make it right.
Let's work together to come up with an agreeable resolution
We can all learn from this experiene
Putting yourself in my shoes I'm sure you can empathize with my situation.
I'm not looking for special treating, only fair treatment.

The issue I had with Canadian tire is that they told me that the belts on my summer tires had warped and they needed replacing. They had less than 20,000 KM but where 3 years old. I was able to get 4 new tires at $50 each. Reason, I was polite and convinencing...

Hell, I even had Visa refund me the interest payment on my Visa bill that I admitted to paying late... Why would they do that? Because I am a loyal customer and my satisfaction is important to them...