It occurs to me that, even if we take your version at face value, a company could easily say that anyone can claim their product was not up to scratch and demand a refund. With a piece of writing it is subjective, and as black cat points out, we don't even know if your opinion was proved correct.
I think you may be on a 'sticky wicket' here. I may be wrong but I suspect you best course of action might be to review them, let folks know they do not supply quality in your opinion. Of course you'd probably have to do that without making it clear who you are and being identified as cheating.
You can try demanding you money back, see what happens. But you may be stuck writing it off as the cost of a lesson well learnt.