Ask a landlord-tenant lawyer and get answers ASAP
Withholding rent is not a remedy for breach of habitability, unless you move out. In that case, your remedy is to declare a constructive eviction and terminate the lease. You have to move out to declare a constructive eviction.
Withholding rent is appropriate where the landlord refuses to maintain the premises in accordance with the lease or statute.
Then withhold rent after giving warning and make sure to put it aside.
Then withhold rent until the repairs are made. Let him know the rent will be paid when the repairs are made.