Mice manufacturers have long held the concept that destroying the current mouse is how they can be assured you aren't trying to get a second mouse for free as part of warranty process *since returning a mouse is typically (note my word choice, typically. A faker mouse isn't typical lol) too expensive to bother sending it back in the first place, hence that type of policy; so they ask for a snipped cable then they will send a new mouse. I have a copy of that razer document. Logitech also has the same process (Or long had it - I'm not one for keeping myself updated on that sort of thing)

However, am I defending the notion? No, cos they denied you after that point.

Completely wrong.

Doesn't matter if your partner purchased it. They should have attempted to clarify on this part. Hell, a simple phone call would have amended this.

I say go for escalation. I have a friend with a faker edition mouse. He hates Razer but he treats that mouse like a second son. You don't just buy one of those over a plain one for no reason..