Is that what your lawyers were arguing? Bit surprising if so to my untrained mind (specifically I mean about the unlawful deduction from wages). I would have assumed it was breach of contract for not paying your contractual entitlement.
The question would be a lot more muddied if you did have a stipulation in your contract regards time limits as to how long you have to submit overtime claims, but assuming there is such a stipulation I don't think it would count as an unlawful deduction, the only risk would be minimum wage rules. But this is just general employment theory crafting really.
