how can i fix the problem?

Hi i have a samsung galaxy 6 edge mobile phone ive paired and bonded it to my ford mondeo mk 4 sony 6000cd and all was working fine as in pressing the green phone button on the sony unit press menu and your phone book is there to scroll through however today ive gone to make a call pressed the green telephine button on the sony unit pressed menu and up come redial last, press menu again up comes active press it again it says rebond and no phonebook ive tried everything is in un bonding from the sony unit and unparing from my phone and repairin/ bonding etc which again is fine but still cant access the phonebook from the sony unit and is now doing my head in as dont know how to recitfy the issue the anyone help please

Graham Moore
September 2017