Normally someone complaining about a score I would absolutely demolish - but I won't in this case. I'm 90% on the side of you and your friend. The only thing I would say against all of this is, do you want to worry these folks over one score, even if erroneously received? It could impact jobs, yes, but I doubt one 8/10 would have any impact.
Definitely follow @Cassiespark's advice and e-mail that group e-mail address. Even though I'm only 90% with you on it, if it were me, I would likely e-mail them, too - only because it is Intellishop and they are good people. I'm sure they would be happy to help, especially when you set the tone that you don't want a wrong score to impact getting future jobs.
My guess is that the editor was working on multiple reports at once, and simply got mixed up as to which report they had sent back.
Let us know what happens.
There is the truth.
Then there is the right thing to say.