(1) A law enforcement officer to whom a surveillance device warrant has been issued (or another person on his or her behalf) may apply, at any time before expiry of the warrant--(a) for an extension of the warrant for a period not exceeding 90 days from the day on which it would otherwise expire, or(b) for a variation of any of the other terms of the warrant.
(2) The application is to be made to--(a) an eligible Judge, if the warrant was issued by an eligible Judge, or(b) an eligible Magistrate, if the warrant was issued by an eligible Magistrate.
(3) Sections 17 and 18 apply, with any necessary changes, to an application under this section as if it were an application for a warrant.
(4) The eligible Judge or eligible Magistrate may grant an application, subject to any conditions he or she thinks fit, if satisfied that the matters referred to in section 19(1) still exist, having regard to the matters in section 19(2).
(5) An eligible Judge or eligible Magistrate who grants an application must endorse the new expiry date or the other varied term on the original warrant.
(6) An application in respect of a warrant may be made under this section more than once.