Mizz, I feel you. We once had a queen (from the animal shelter) that started peeing on the hall carpet once she felt at home. We took her to the vet, no medical problems, she just wanted to mark her territory. We knew that she'd been thrown out by her previous owner after they'd found out she was pregnant (yes, a genius move not to sterilise your cat) and felt sorry for her and had already grown attached to her, so we just kept buying her cheapo carpets from flea markets. After a while we got used to the cleaning and buying new carpets. She was four years old when she came to live with us with her daughter and she died at the ripe old age of fifteen years and nine months. Yeah, I know. I just can't get angry with cats, no matter what they do, but I understand they can be a pain in the butt.