Hypothetically if our commercial tenant wanted something that had a contract clause that it would be pending approval with body corporate. But then went and deducted rent per week to compensate for not getting it, without approval of this, is this legal?

Contract signed pending approval with body Corp.
Outcome is not favourable for them so they start to deduct rent to cover for what they wanted in the first place. No approval for this to go ahead. Is it best to issue termination of the contract or at least a few warnings as tenant has not paid contracted rent amount?