Are you abandoning the property and notified the landlord of so doing? That makes sense when the lanblord tried to sublet the apartment with increased rent. But why are you invovled? If that is the case, you will not win. Modern statutes require the landlord to use good faith to mitigate by subleting. What is good faith obviously is fact oriented explanation from the court so that unless you can prove his bad faith with predonderance of evidence, you can not win. That he did not want you to call does not consitute bad faith. It is, most likely, that he did not want to get the nuisance from your phone call.
Read your leasing instrument carefully to find out more information. From what you said, it is hard to describe what is really going on.