Changing my duty time on a Saturday

[superteamu10]

Can my DOM just decide to change my Saturday start time from 5.30 to 7am? She basically doesn't want to pay the 2 hours overtime to another driver who does a collection at 12. She wants to add it to my duty instead by having me start later.
Because we haven't gone into delivery methods yet I don't have to do many 2nd bags as so many use their cars. This is not my fault and I didn't sign for the duty in the belief that so many would take their cars.
We have no rep by the way, so this is the quickest way for me to ask where I stand on this?

[IloveMYredTROLLEY!]

"Sorry boss, I have weekly commitments after my standard Saturday hours, starting and finishing 90 minutes later conflicts with my longstanding commitment."

[beanmuncha]

Does it not say somewhere that you need 28 days notice for a change to a duty?
i'm not 100% sure but i remember something like that

[clashcityrocker]

The change to your duty should have been discussed at the Resourcing Meeting with your rep.
Your views should have been sought.
If you are not in agreement with the change the rep can put in a disagreement. This gives you 28 days to exhaust the IR framework before they implement the changes.