Cancel & Return Storm-Ready WiFi

I am extremely frustrated with this situation. I purchased the Storm-Ready WiFi from a local Xfinity store only because the salesperson explicitly told me I could return it anytime if I didn’t want it. Now, after never even using the equipment, I’m being told I can’t return it?  I feel misled and deceived. I made this purchase based on false information, and I will not accept being stuck with something I was promised could be returned. I want this service canceled immediately and clear instructions on how to return the equipment.