If it's still unresolved, you should know that Stuart Lee only processes the rebates on behalf of Wireless Advocates, the firm that operates the kiosks for Costco. If the reason for the refusal is in error, you should go back to the Wireless Advocates DM who should be able to confirm that your data plan remains in place.
This doesn't apply to your situation, but rebates may take 12 weeks, according to the paperwork from my last rebate.
Finally, I loved your joke about no contact number is "standard SOP [sic] for fraudulent companies everywhere." LOL! That would include nearly every software company on the planet! You ever see a number for Yahoo! or Google?