Ownedcore reviews need to be taken with a grain of salt. The big providers on the forum are either friends or have business ties with the "Mods" wherein they remove negative reviews/don't give a dahm about the customers.
The unbanning services do provide a legit service in that the gross majority of people who've been banned don't know how/when/what to say in the appeal; but at the end of the day, The unbanners act like they have the exact perfect forumla, when in reality; they've just done a large number of bans so have some common elements that work well; but its very case by case and support tech by support tech.
I've tried with the "original" provider of those templates. Went back and forth with two GMs with about 5 messages each from the guy and they stood their ground. I'd imagine it might work for a small percentage of people but for the majority it won't. Good luck with it though.