Memebership Cancelled

I am a brand new member of Good Sam Club. I received an offer that I would receive a $25.00 merchandise certificate if I joined. Got my cards in the mail along with certificate. Great! I need a couple things so I went online to Camping World and when I entered the coupon code it said wasn't valid. What? Called GS and they transferred me to Camping World. Was told, like above, have to pay full price then mail them the certificate. What kind of bull is that? The certificate doesn't mention any restrictions. In this electronic age there is no reason to not be able to apply it. It may not be a major problem "first world problem", but it definitely is shady practice and leaves a sour taste in my mouth. Thoughts of cancelling my membership, not sure yet if I will, but not sure I'll renew either. By the way, this isn't a "coupon", it's a "rebate". Maybe if they were just honest about it.

And this isn't some "low level" employee making a mistake. This is company policy.