We have just had a drain specialist in greater Manchester who said that our builders (uncontactable) laid our 40mm pvc waste pipe from the kitchen island to outside (about 3 meters, suspended floor, just about a crawl space underneath when floor lifted) too flat and there’s standing water, smell etc. they’ve quoted £2250 to lift the floor and replace the pipe. Sounds way too much for me but wanted to know what a reasonable quote would be. Thanks