Unable to redeem code on Steam

I just went through the process on SHiFT to sign up and received a code for the closed technical test. I followed the instructions to redeem the code via Steam and upon entry of the code, steam states the following:

Purchase Error
An unexpected error has occurred. Your subscription to the following items has not been completed.

Please contact Steam Support using the link below.

Yet there is no product listed there and it’s not in my purchase history so I have no ability to contact steam about the issue. Their support pages require you to contact them about a specific product in the purchase history.

You can also reach out to our support team if that’s easier for you: http://support.gearboxsoftware.com