You do know that it's not going to be the person in the call centre's fault, don't you? And that the ruder, more obnoxious a caller is, the less inclined anyone is going to be to try to help them out...
At least start being polite and adult but be reasonable in terms of what you expect to get out of it. If you just want to let steam off without achieving anything (which is what will happen if you just call and shout at the first person), you'll save yourself cash and someone else some pain by not bothering to dial first.
Somebody explain...how when I placed my order at before 08:10 and I have a mail at 08:12 confirming the order. I don't get my order tomorrow, when it is suppose to be first come first served. Lottery comes to mind!