Outstanding Demad

I  have received demand notice of about 13k in 18-19 FY. While filling revised returns  I paid about 7k which was come as per my revised calculations. That revised ITR was rejected. Now i got mail for payment of outstanding demand. While i go to the My work list section can see 13k as payable amount while I have already paid 7k. How can I pay pending 6k? Or what would be the process to settled the issue,?