Redeeming 30 day Hallmark+ subscription on Roku Channel

I purchased a new Roku Premier in-store at WalMart that advertised the 30-day free trial on the box and included a card inside for how to redeem. It said to accept the free offer after activating the device, but I never received the prompt to accept it. To resolve, I have:

-exchanged the device at WalMart. Experienced same problem with 2nd device, no redemption screen.

-contacted  Roku Chat, after a considerable exchange was told the only thin they could suggest is that I accept a 7 day subscription and they would reimburse me if I was charged for the 30 days. I found that incredulous, so contact the telephone support. They told me they could not help, that I had to contact WalMart.

-contacted WalMart. After speaking with 2 customer service agents, I was directed to contact Roku as there was nothing they could do with a Roku device. I was willing to call WalMart because I thought they should be aware of this promotion issue.

-also contacted Hallmark - they only offer 7 day. To get the benefit as advertised by Roku, I have to contact Roku for assistance.

-contacted Roku again. They are telling me I have to be a WalMart member to redeem which is not accurate. I have asked to speak with a supervisor and am on hold.

This is kind of crazy and shouldn't be this difficult to redeem a clearly stated offer on the Roku box.

Can anyone help me?