My dog has a serious problem

[Lobzik]

Hi!
I'd like to start with introducing my dog and me. My name is Vassili, and I always wanted a dog. Almost 3 years ago we got a dog. A Jack-Russell Terrier. He was all cute(and still cute)no spots. We started training him, and it was going fine. Until a certain point. He kept on peeing in the apartment. We were walking him, almost 6 times a day, and still nothing. Then we moved into a house. The house was only temporary. We still live in it. My dog is almost 3 years old now. He still has that problem. The house is not ours, but i assume the dog doesn't understand that. So he pees on the carpet!!! He already marked his territory, in several places, we had to put away carpets, and lock them in the basement. But there is one that we can't just take off. It's on the stairs. He found himself a nice place their, and pees when no one is looking. Sometimes he even poos. Although pooing is not that bad, because it's solid and does not ruin the carpet as much. We have taken many measures. We started walking him more often, we are being stricter with him and his diet. We tried punishing him, and "asking nicely". Still nothing. Then we took him to the vet. The vet said, that it's his behaviour, the dog is absolutely healthy. We even sprinkled the carpet with pepper, it worked for some time, then he started again. I don't know what to do. The house will be a disaster, when we return it. We went on a big risk, because we are not supposed to have any pets in the house(you didn't hear that from me!). We are keeping him secret. We only did it, because we had no choice. Either we move in or pay another monthly rent for the apartment. The dog is absolutely ruining the house. He ruined 2-3 carpets already. I can't take it anymore. He is 3 years old!!! I'm ready to do anything, a cage, that electric collar that will zap the dog, anything. I understand that it's cruel, but the amount of money we will have to pay is absolutely enormous! Please help me.