Refund of wrongly paid gst amount

I paid the late fee of Rs.800/- by entering in penalty column instead of Fee column in Challan for the month of August. After that, I tried to set off balance but site didn't allowed to set off showing available bal as ZERO in late fee column. Later again i paid 800 by generating new challan in Late fee column & im able to set off. Now Electronic cash ledger showing Rs.800 Balance in penalty column. How i can get the refund for that. We cannot use this balance for next month GST[ payment as challan generated with Penalty column we can able to setoff with Penalty only but not with CGST, IGST, SGST or Late fee.