New Water Plumbing

My building hired this company in February (New Water Plumbing) to fix a plumbing issue, so they shut off the hot water. When it was restored, both my kitchen and bathroom shower had no water pressure. I alerted the building and they hired NWP to resolve the issue, informing me that I would have to pay for this service. The plumber flushed the kitchen tap, but said he couldn't restore full pressure as the tap itself was clogged with sediment and I would need to replace. He cleaned the cartridge in the shower, which restored the water pressure. It cost me $600. In the last day (four months later), they were back fixing something else in the building and shut down the hot water again, and AGAIN my shower has no water pressure. I asked the PM to send the plumber by to resolve the issue before they left. I told him the issue, he paid no attention to what I was saying. He turned the tap on and off a few times, but I kept telling him it was a hot water/sediment issue. He said nothing. Frustrated with being completely ignored, I said again more forcefully that I know what the issue is, he walk up to my face and said I needed to be quiet he knows what he's doing, he was trying to get the sediment out of the tap. Of course, turning it on and off didn't work and he walked out saying that he was hired by the building and he didn't care if individual units had issues with sediment and water pressure, it wasn't his problem. I went up to speak with the PM, he arrived and again was really rude, telling me again he knows what he's doing (although my water pressure issue wasn't resolved). The PM is going to hire another company to resolve my issue, which will cost me more money. This company's plumbers do not know what they are doing and they are rude.