Kazemie

My wife received a letter from “past due credit.co.uk” saying that she owe £460.73 for water usage in our previous home address and they are going to collect this money on behalf of United Utilities Water Ltd. She was not even bill payer in our previous home address and we already cleared our remaining balance once we moved to our new home. Would it be a scam? Are they even legit? Do we have to do anything or just ignore them? Could you please help us as we are really scared of sharing our contact details with them by calling them?