Absolutely horrendous... And i'm not surprised they are treating you like this. I suffered a similar fate and do not use them now.
3 or 4 years ago when they were fairly small they were great but greed and ignorance have replaced good old customer care and service.
I suppose we can't say don't buy from them as this thread will probably get closed but we can recommend other places to shop from ok guys?.
Back to your sorry tale, i know what i would do. I'd go down there and demand to see an engineers report for said items but get your own as well that shows that they are faulty. Then you can ask why they charged you when you shouldn't have been and you have better grounds for a FULL refund.
Bloody good luck to you mate.