ok - the cable coming out of the wall box is what you need - follow that and find the other end and fit that into the hub - if the cable is damaged or too long remove it from the bottom of the wall box and fit the new one - the new one is push fit - the old one may be that or a screw fit - they both fit the connection on the wall box
you may have to activate the hub - 0800 953 9500
all being well that should do it
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Tony