A plumber from a licensed company recently did some work in my bathroom. He also decided to check my water pressure (which was 55 psi) and recommended that I have him turn it up to 65 psi (to which I agreed). Yesterday (about 2 months after) I had the connecting line of my toilet burst, which resulted in some minor flooding (I happened to be home). Upon buying a replacement I was made aware that the water pressure must be too high. I contacted the same company (different worker came), but they told me that the valve was broken and that the water pressure measured close to 80 psi, not the 65 psi the previous guy said he set it to. I complained to the company, but they said his invoice only talked of the bathroom repair and him measuring the water pressure at 75 psi, not the 55 psi he told me. That makes me think that he knew he broke it that day and adjusted that measurement closer to the 80 psi it is at now. All the company does is quoting me a replacement of the valve of 1k (which is even higher than any other company). But that valve was working perfectly fine before and they broke it. But since their invoice made no mention of him changing the water pressure they rub their hands clean. What can I do in this situation?