Rebates and discounts are such a PITA. Personally, I wouldn't bother with all this fuss over $8. I know, it's easier said than done, and yes, it's a matter of principle, but I reckon you will have wasted enough time, effort, and sanity that, if one could put a price on it, would come out to roughly $37.94
Unless you either get your money quickly or just let it go, it's a lose-lose proposition. Either you may never get your money back, or it would have been too much trouble to do so that it would not have been worth it on your part.
So, if you can use revisionist mathematics and arbitrarily assign dollar figures to frustration and wasted time and effort, you too can set your mind at ease by stopping to bother with customer service agents that are specifically trained to be vexatious to the spirit.