When I call up any company for a customer service issue I am always super nice and polite, even when they can't get something done or I'm on hold for ages. I've never had to work in customer service (thankfully), but I have a few friends that have worked in customer service call centres and they say it's the worst job ever.

When it all comes down to it they're just the bottom of the rung employee working for little pay, in a job they probably hate. They certainly don't need me shouting bloody murder down the phone because they can't send out a guy to fix my washing machine until next week.