[mothered]

Yes told me to return it and no just gave me a label to put on it

So all they did was provide you with the label to attach, and no Instructions as to which carrier/service to use?

If so, then you're well and truly covered, by sending It via RM with no tracking.

Yes just a label to
Print out.

You're good to go.

Given you're (seemingly) using RM without tracking and Corsair did not specify the carrier, I don't see any reason why this should fail.