Have you tried changing the WiFi channel used by the BT kit. Try them all (1 thro 11). Sometimes you get interference from other electrical equipment (cordless DECT phones, Microwave Ovens) so also try moving the BT Hub around a bit. Or even nearby WiFi.
You could attach a proper Access Point to the BT Hub, simply use an Ethernet cable between the connectors on both units, then set up the AP.
But I'd try making your BT kit work first.