The Senate often indicates its disagreement with a bill by rejecting the motion for the second or third reading, and that action is taken to be a rejection of the bill.
A senator may also move that an order of the day (a matter which the Senate has ordered to be considered on a particular day) relating to a bill be discharged from the Notice Paper, pursuant to standing order 97(4).
When the two Houses do not initially agree on the contents of a bill, it is usual for negotiations to continue. Amendments to amendments may be made or alternative amendments proposed until an acceptable compromise is reached. Occasionally, the impasse cannot be broken and a bill is laid aside and not proceeded with.
Brief Guide to Senate Procedure No. 16 - Consideration of Legislation
Senate Brief No. 8- The Senate and Legislation