A friend at work scouts Best Buy, Office Depot, Staples, etc. for deals on consumer electronics. These deals often have rebates attached to them.
For high-dollar rebates, he always keeps records of his submissions. He has fought back and won at least once. The amount of the rebate was $60. “You'd better believe I'd call them for that,” he told me.
Companies have little to lose by refusing to pay their rebates on technicalities. If it turns out later that they were wrong and you actually do deserve the rebate, well, oops, sorry about that, here's your money. But you need to follow up, call them, and prove to them that you had your ducks in a row. Otherwise, you just paid full retail.