Hi Tarina, from the tone of your reply, it sounds as if you're expecting fast results. It's going to take time. Koppa has learned to behave the way she is because that way she is getting attention from you & any attention is better than none at all. You did well to ignore the chewed chair & ignore her but then you gave in & gave her treats. Treats must only be as a reward, not because you feel sorry for her or guilty about ignoring her. These cockers, with their melting brown eyes, can soften the hardest of us, but we have to try to be a bit harder for their sakes.
Koppa needs to learn that she will get your attention when she's been or being good but not otherwise, if anyone has a link to a NILIF thread that would be very useful, meanwhile, I'll see if I can find one. The basis of NILIF (which is an acronym for Nothing in Life is Free) is that a dog only gets attention when the owner wishes. The dog is not allowed to seek attention, only the owner can do this. You know how they paw at you when you're on the computer or something? Well, with NILIF, they are no longer allowed to do this, you, as the owner, can call the dog to you for a cuddle, a game or anything, but the dog is not allowed to initiate play or any kind of attention. I've never been strong enough to make it work myself but I'm told that it works and with some dogs it's the only thing that does work.
Please also consider getting a crate for her, I've not yet seen a dog who was unhappy to use a crate. If you go to Crufts, you will see loads of dogs in crates, with the doors wide open, they can get out if they wish, but they feel secure in their crate, it's their territory.
Keep on posting Tarina, let us all know how you're progressing with Koppa, you'll get loads of help on here, we're all rooting for you.