cannot connect my wifi ext to new router

HELLO please can anyone help me with the problem in having, I have 2 netgear extenders which worked well when with sky, have changed my provider to the utility warehouse and now cant ge the extenders to work, it keeps asking for a password which we put in but it says its incorect, feeling very desperate and need to get these to work or will cancel my contract and go bacl to sky......PLEASE PLEASE HELP