IIm not sure what the laws are in your country. I would consider challenging the bill itself as hack account unauthorized action. To that you are putting the charge into dispute status. Explain how your account was comprimised by 3rd party. Explain that you will Never ever pay the charge as you were not the user. Likely they will give you a "one time exception" and charge of f the debt. This is coming from someone who refuses to be screwed by bill collectors. I am confident you will win either route. How much do you owe for the bill?