Tefal Burned My Milk in Daily Cook Pots - Refused to Take Them Back

Three days ago, I bought the Tefal Daily Cook stainless steel cookware set. After purchasing it, I boiled milk in two of the pots, and in both cases, the milk burned at the bottom. The base is extremely thin, which makes it unsuitable for delicate cooking like boiling milk. I followed all the usage instructions carefully, so the issue is clearly with the product quality. I had a lot of trust in the Tefal brand. I’ve previously bought many pans and pots from Tefal and even recommended them to people around me. This time, however, it has been a complete disappointment. Please help me. The store where I bought it refuses to take the product back.