There was a lot of complaint about SOPUS MIR denials and simple lost submissions here years ago.Pennzoil has ripped me off WRT their rebates as well. Horrible way to do business. I have a long memory.
If the intent of a rebate is to promote goodwill with buyers, then I would think that they'd be a little flexible in implementing their program.
A rebate denied brings bad will far in excess of the cost of honoring the rebate.