Receiving letters from O2 for someone not in the household

[Lilyoh]

I've received 5+ letters from O2 at my address for someone who doesn't live here. I've marked them all as not known at this address and returned to sender, but they keep on coming. Any help/advice? Really concerned that someone may have credit/a contract registered to my address.

[jonsie]

Try calling O2

Give the customer details and they can inform the mail centre

Guide: Coronavirus Community Help and Support