I have taken the option to get any pricing difference credited, based on Dell's word in the past, with no email or fax to document it, and it has worked, though every time I worry. Three times so far it has been ok.
On the topic of customer service, I got in on the Dell WD 120 hard drive deal and got bumped around, transferred, lost, and had a supervisor literally butt in on call with a CSR WITHOUT any warning or identifying herself. She then faxed me the wrong rebate form. I got a 10% coupon from Dell out of it after someone much further up said they would "have a serious chat with her," and an apology.
Dell runs hot and cold on customer service. Other times I have the most polite people and deals or extra coupons stacked on a deal in less than 60 seconds. Its probably the best example I know of , of a big outfit that occaisionally posts deals that are too good to be true but if you can get them for the individual are awesome.
It just takes more effort than it should or clean up after the fact than it should because once the deal is posted and out of the bag so to speak, doing all the things I read about Dell doing on here in the manner of customer service treatment doesnt help, and I dont just mean this cases where a discount or stackable coupon is the issue, these Sony DVD drives they sold and this WD drive/rebate are the type of things they post over and over but never seem to learn to handle any better with time.