Tired of invoices after cancelling my sim card and not using the services for many years

Really tired of getting invoices from Rain, even though I have cancelled my sim card and account. I haven't used rain in more than 5 years! After contacting Rain support, they were not able to find my cancellation confirmation, even though I provided them with the reference number THEY sent me!

Reference number: ***3 sent from Rain support themselves.

Please cancel all my services and delete my details from your system.