@jac_95 Going back to your comment...shall I also contact BT and request they do data integrity checks on the address and explain I have ONT and provide the serial number?
As already been stated, only the provider who you are wanting to take out the broadband service with can perform this.
BT Consumer, the ISP, that this forum is for can only help and support existing customers or users wanting to sign up to BT broadband.
Are you or your tenants wanting to sign up to BT broadband?
@jac_95 yes we are wanting to sign up to BT as has the best offer
Whoever is opening the account in their name with BT broadband you can try the FTTP team on 0800 587 4787
Provide the guide (customer service agent) the ONT serial number and explain that they may need get DI or raise a ORDI request due to the address issue.