Hi Sam... I do understand that you have a very strong case.
If you have stayed in the rested house for around 20 years then it is very much likely that you have easement rights to enter the rented house.
Firstly, you need to be sure as to what are the documents you have relating to the rent. As the matter in question relates to tenancy hence, the document (rent agreement) is not necessary required to be registered as per the Registration Act.
Secondly, if your landlord doesnot accept the rent, you can deposit the rent to the rent commission favouring your landlord. Through this way the landlord cannot evict you on grounds of non-payment of rent.
Thirdly, you need to consult a good lawyer who will gide you regarding this case. I do understand that in the Indian courts rent matters take a long time to be solved, nevertheless this should be a boon for you as the landlord cannot evict or demolish or re-build the existing building before the case is over or till the time both parties reach to a settlement.
Forthly, there are lawyers at Maharashtra who deal with such cases every day and I am pretty sure that their fees would not be a hefty charge on your pocket as because the rent revision arrangement in your rent agreement is 20 years old. So you will have to pay more for a similar accomodation at a new place if you leave your current accomodation.
Hence, I would advise you to get in touch with a lawyer and iniciate a case on the landlord a.s.ap. for change of name of the tenant and you can deposit the rent to the rent commission. If you do this exercise then you will not be a defaulter of rent and the landlord cannot evict you. Also, in your petition you can include that due to this harresment caused by the landlord you are forced to take legal steps and all such legal cost shall be paid by the landlord.
Hope your query was answered.
RoyS