Is it permissible to use the interest and the due Zakat on money saved in the bank to spend on the house and its repairs, such as buying a refrigerator and living room furniture, knowing that I am the sole provider for my parents given the difficult financial circumstances of my siblings?

It is not permissible to deposit money in an interest-based bank. If one is compelled to do so, they should deposit it in a current account. If interest-based gains result from this, one must repent and dispose of them by spending them on the needy who are not financially dependent on him, such as needy siblings. As for parents, it is not permissible to give it to them because they are among those whose financial support is obligatory, and it is not permissible to purchase personal goods with these interest gains or with zakat (definition) funds.