I have an existing home loan (23L) + top up loan (12 L) from a private bank, totaling to 34 Lakhs.

Of this 12 lakhs top up loan – came to know that we can claim both  principal & interest part under section 80c & section 24 respectively of IT act. is that true?

My bank refused to give me provisional IT certificate for my top-up loan account, so how do I make the claim?

I had utilized the same for house construction, can you tell me the steps to make the claim next year?

specifically, what should be the document from bank (similar to provisional IT certificate)?
would a self attested declaration from my end suffice as proof that it was used for home construction?

Thanks in advance.