New regime taxation

i filled ITR under new regime and claimed 24500 exemption under section 87a for normal income and special income under section 111A.

bur when I recieved intimation from department that have not allowed exemption of 15000 for 111A.

I filled response that it is incorrect but i have not received any response till yet and when I am filling revise return of income system is not allowing to change old regime of taxation

pls advise anyone how can I save this 15000 tax levied by department which is error by portal.


Regards
CA Pranav Aggarwal