TDS -whether legitimate or not

No . It's not legitimate ..

How much is your age ?

You have wrongly filed 15 G ,two conditions to be satisfied for getting benefit of 15G
1. Your total income including the income for which 15G/H is filed is after exemption or deduction is less than non taxable amount ie. 2.5 Lacs

2. Your income under 15G/H should be less than 2.5 Lacs ,

suppose Mr.x has salary income of 2 Lacs and interest income of 1 Lacs then he can file 15G/H

If here in this case interest income is 2.6 Lacs and salary 2 Lacs ,he can't file 15G/H and bank will debit tds @ 10%...even though total tax payable post rebate is nil ...

Tax deduction must be done by banks and you should not have submitted Form 15G unless it is 15H

15G AND 15 H ARE SEPERATELY FILE.
BOTH HV DIFFERENT IMPLICATIONS.

One should not file wrong declarations through 15G or H for not deducting Tds