School not issuing school certificate

My son has been promoted to class 9th. I have decided to move him to another school in pune. I have paid a small amount and got the registration done in the new school. When I went to the old school where he was studying the office staff first informed that if you are moving your son to another school in pune then we will need a demand certificate from the new school and if you are moving him outside of pune to any other state then there is no need for any certificate. They said I will get the certificate within 8 days. When I went back after 8 days and asked them about the certificate. They first asked where I had taken the admission. I informed them that I plan to move him to a school in South india as that's my home town. I also told them that it's a plan going on and we have not decided on the school yet to take the admission. On listening to this the principal interfered saying there is a new rule which states that I get a letter from the principal of the school I will take the admission saying that plz issue transfer certificate. Just imagine how difficult this would get if i were to actually take admission for my kid in kerala. I will have to come back to take TC for my kid after getting an approval letter from school in kerala. This has angered me to quite an extent. They know I am a single mother and they are making it worse for me. Can anyone suggest if there is any such law which says that TC will only be issued after getting approval letter from the new school we are taking admission? Can you suggest me my next course of action to proceed legally. I am not taking this lying down anyways but I am also not spending any money on this. Thanks in advance for any advise and suggestions.