Wrongly paid different challan for the outstanding demand

As one of my client has filled it's ITR for AY 21.22 but due to some error there was a demand notice issued to him amounting to Rs. 5,000(assumed) & he has also paid challan for the same but while generating challan he had wrongly paid challan in different AY now the Payment has been made but the demand is not resolved yet

He has also sent an written application mentioning the facts in the Zonal office of Income tax but they have said him on call that we have adjusted the same challan against the demand but it will not reflect on portal

In short the authorities are not responding properly like mentioned above now what are the remedies are available requesting to share your opinion for the same


Thanks in Advance
Khush Trivedi