R V Gas Strut Regas

I took his recommendation to fit new struts with a 12 mth warranty. When they stopped lifting he came and regassed them. They stopped lifting again a week later but he said one regas was all the warranty I was entitled to. He said we opened the tail gate too often and the struts are only intended to lift the tailgate a couple of times a day a few days a week. Faulty struts should be replaced. Not happy.