Oh the dilema!!!

Ok...So I have 2 cats. Kip and LaFawnda...(hardy har har). I love my kitties, even if they don't really love me. LaFawnda has been a struggle though. She is a beautiful black cat, and is more loving than Kip. She can be so sweet. But in the last 2 years, she decided that our wonderful Lovesac is her cat-pan. We had it for about a year before she decided this too! We've cleaned and cleaned that damn thing, and she still pees on it. It is to the point that I can smell it all the time, but everyone else says they can't. Well, today on my way home, Rob calls me and says "you're going to be so mad" and I said, "oh hell, what??" and he told me that she peed on it AGAIN! AND POOPED ON IT!!!!!! WHAT THE HELL?!?!? We bought the damn Lovesac for $425! She's freaking ruining it. Most of the time she pees in her litter box, its only once in a while that she does this. I'm at my wits end. We even took her to get fixed and guess what? she had already been fixed!!!! When I got her at the shelter they said she wasnt fixed yet. So, that's not the problem. She's done it a few times in a corner of my apartment, but it's now just on the Lovesac and NOT all the time. I've tried it all, all kinds of sprays, vinegar, putting a blanket she likes to sleep on, on the sac. So now the debate.....do I take her to a shelter?? I DONT KNOW WHAT TO DO!!! :(