Do I curse Michael's NOW, or wait until Sunday?

Last month, I got an email from The Knitting Guild Association Club Group Team Squad, of which I am a member, informing me that:

Michaels Arts and Craft Stores is offering an opportunity for all members of The Knitting Guild Association (TKGA) to donate their time to a worthy cause to teach knitting and/or crochet to customers during our annual October Yarn Event. The emphasis will be on teaching customers to complete squares for the 'Warm up America/Blankets for Canada' charity.

I think, "What the hey! Good Karma, 20% off my purchases that day, what's not to love!" I sign up. It is scheduled for Sunday 10/15.

I got an email from Michael's Yarn Commendatore, confirming my participation and inviting me to check out their website to learn more about their fabulous amazing to-die-for yarn event. So I go... and see this:

The Yarn Doctor is IN! Don't miss your chance to consult with the Yarn Doctor at your local Michael's on Sunday, October 15 from 1-5. Bring in projects for expert assistance, or learn the basics of how to knit. . ."

Ummmmm... You talking to me? Sure, I can "Yarn Doctor", but if I am giving "expert assisance" to Michael's customers on their existing projects, then I'm providing a service for publicly-traded for-profit Michael's. Which is not quite the same, karma-wise, as teaching newbies to knit rectangles to be made into blankets for the homeless.

Yeah, I can see myself getting into a shouting match with the Michael's store manager, as I explain to him that he should check with tax and employment counsel, because one simply cannot volunteer for a for-profit publicly-traded company and that he'd better give me my 20% before I inform some FLSA class action lawyer about this.