Some, not all but some. Although I'll bet going onto the phone shouting and screaming is more likely to get you on the bad side of some of them. They are only human and if you give them a hard time on the phone are they more or less likely to help you out?
I have to disagree on that point in my experience whether you are polite or not the job doesnt get done all you get are false promises(and hear in the background, are we out tonight, hurry up we are going, quick sign out its diiner time, they dont give a dam about the paying customer, but would'nt it be fun if they had to call a call centre and have to put up with a little of there own medicene
, nthell pay peanuts thats why we have to put up with the monkeys at the other end of the line.