Looks like its a gift card they send, rather than a check, have you tried using this number yet?   

https://proconnect.intuit.com/referral-program/

I know I did a survey thing for Intuit once a few years ago and they sent me a virtual gift card to my email, I think it came through a 3rd party though, not Intuit directly, you may want to dig through your bulk mail folder just in case they did something like that for this.