A milk supply agreement is defined by the Dairy Code (section 5) as a contract between a processor and a farmer for the supply of milk.

Sections 16 and 17 provide, that a processor must not purchase milk from a farmer other than under a milk supply agreement which complies with the Dairy Code.

Section 18 provides that, if a processor enters into a milk supply agreement with a farmer that is not in writing, then no later than 30 days later, the processor must:
(a) make a written record of the contents of the agreement;
(b) give a copy of the record to the farmer; and
(c) if the supply period of the agreement is 90 days or longer—make all reasonable efforts to obtain from the farmer a written acknowledgement that the record is a complete and accurate record of the contents of the agreement.

To proceed with a complaint under the Dairy Code you must have evidence in writing of the contents of the milk supply agreement between the parties and when it was made.