When will rectification option be available in new portal

I made a small mistake while entering self assessment challan number and they are asking for tax demand in 143(1). Now I want to correct the challan number. But for AY 21-22 the portal is not allowing for rectification. What to do in this case? When will they support it?

should I just revise my whole return instead and then respond to the demand with revised return number?

please suggest