School not providing TC for my Children

Hello Sir, I'm Sujith Kumar, working as a technical manager in a private computer institute in Mangalore. I migrated to Mangalore from Kochi last year and admitted my twins (daughter and son) in Narayana Guru Primary School in Kudroli , Mangalore in first standard (Unaided Private School). While admission the HM demanded the original copy of the birth-certificate in their permanent custody but I had only one original copy , so I submitted the original for verification and provide a notarized copy of the same for them to keep, they did not agree for the same and demanded me the original ,but they took admission and my kids completed their Class I. This year I shifted them to Canara CBSE School ,Mangalore and admitted them in Class II, When I applied for TC. they refused to give and demanded again the original birth certificate. Even if multiple copies of birth-certificate can be obtained , my case I will have to travel to Kochi and at least spend 2 -3 days to apply and get it , I will have to spend at least 3-4 k for travel,stay ,food etc and also will has to take 2-3 leaves from office, so requested many times to the HM that I will show the original and submit notorized copy , but they did not agree and HM and the managment where angry with me for shifting the students to a better school. I want to know whether an original birth certificate must be handed over to the school for their permanent custody (will never return it) , no other school is Mangalore is demanding the same. If it is a strict rule, they should have denied the admission last year so that .I would could have found another school for my children I want to know whether I can complaint the education dept on this ,or should try to obtain an additional copy of birth-certificate, Please explain me a solution, the new school is asking for the TC, I have already paid the fees ,got the books and uniform form new school.