Low quality Towbar

I took my Ford Everest to Steelite Tow bars to have a tow bar fitted. On receiving my vehicle back I complained about the thin material used to build the tow bar. The manager told me that I have a guarantee and that there is nothing wrong with the tow bar. The first time with a quad trailer it bend down with 50mm. The owners comment was that he is 30 years in business and will weld in some supports but won't refund me. Some how on connecting up the electricals they blew something as the \convenience"items like rear view mirror adjustment and auto door locking is not working anymore. I don't want to know what would have happen with a big caravan on tow!! I got another tow bar and the Steelite one is not close to as what it should be and I want him to refund me.Deon"""