13.—(1) Without prejudice to the provisions of paragraph 12, but subject to sub-paragraph (2), a court of summary jurisdiction for the petty sessions district concerned may, on the application of the offender or the + responsible officer, by order amend a probation order—
(a)by cancelling any of the requirements of the order; or
(b)by inserting in the order (either in addition to or in substitution for any such requirement) any requirement which the court could include if it were then making the order.
(2) A court of summary jurisdiction shall not amend a probation order under sub-paragraph (1)—
(a)by reducing the probation period, or by extending that period beyond the end of 3 years from the date of the original order; or
(b)by inserting in it a requirement that the offender shall submit to treatment for his mental condition, or his dependency on drugs or alcohol, unless the amending order is made within 3 months after the date of the original order.
(3) In this paragraph and paragraph 14, references to the offender’s dependency on drugs or alcohol include references to his propensity towards the misuse of drugs or alcohol.