Should you "almost empty" the building savings account?

My employer also only pays the capital-forming benefits into old contracts for me. However, I was still able to cash out my home savings contract. My person from Wüstenrot simply concluded a new contract with me, which, however, continues internally only with a new contract number, and the company thinks the amount continues normally under the old number, so they don't notice anything about it. It's somehow possible like that.

I would also not mention the BHW! Rather my idea with the installment loan. It costs 3% with the option to repay at any time.

What is the interest rate on the [Bausparvertrag]? Is there also a bonus for not using it? What amount is it?