As you have evidance of cheques. So don't worry.
If you file eviction suit against tanent at any cost they ahve to pay same rent in court. So through court you will get that rent whatever they paid by cheques earlier. So there will not be much financial loss for you.
Once you file eviction suit against tanent, they will definitely come negotiations.
I am telling you don't bend your head. As a owner protect your right. But is proper manner you have to proceed.
Don't demand for high rent through court. That will give a chance to tanent to drag the unnecessary arguments.
Under T.P Act you ahve special rights. U can give 30 days time and ask to vacate as premises is required for your own perpose.
As the agreement is unregistered that is advantage for you not for tanent.
Don't afraid. May be case will run 1 or years in court. Let it be.
Once your tanent vacate the property , can get more rent what you are getting now.
In my openion only one choice u have is to file eviction suit against Tanent. Otherwise you have to loose your respect and money. Don't thing too much.