Ring the head office of the bank in question and ask where their Securities Department is. Then ring the Securities Department and ask for the manager. Tell them that you'll be calling to their office in two days and will not leave until you collect your deeds.
I assume that the bank are only holding the deeds for safe-keeping - if there's a loan secured against the property you won't get the deeds back until it's cleared.
). Apparantly it takes 4 weeks for this to happen...