Invoice 1+ Year after cancelling contract

I left Germany 9 months ago and cancelled my contract with o2 more than 1 year ago. After signing up for a DSL contract I waited 3 months for internet to be installed in my apartment and after a lot of difficulty dealing with o2 I cancelled my contract and returned the router to o2. Now, after having left Germany you are sending me invoices more than a year after I have cancelled my contract. I have no login details, your system doesn’t recognise my email address and I can’t even view these invoices – just the emails that you want me to pay something.
Please can you explain why this is happening and cancel whatever invoices you are asking me to pay? I have already settled everything with you many many months ago, not to mention that you never provided me a service.