What I would have done is to immediately photograph everything in the package, pack it up, and return it for a refund as per Wiggle's "Return Policy".Hmmm... I don't believe that.
Using your analogy, if I had received my "new" ebike as open box with some missing accessories or parts, I wouldn't have been happy with the seller and complain, then send everything back and get a refund.
Not everyone would just suck it up!
I think the OP did the right thing to share his deplorable experience buying from Wiggle.