I assume they are powerline adapters
You can only have one powerline type adapter connected to the home hub, that will be the master. All others must be slaved off that master unit. You will run the risk of an Ethernet bridge otherwise.
Which BT home hub do you have?
Is it a home hub 5a or 5b?
What sort of extenders do you have, and how are they connected?
Where does the wifi come from, is it from the home hub, or another device?