Can I approach High Court for waiver of cost after dismissal?

I am a senior citizen woman, representing my case as party in person. Could I file an application for waiver of cost after misc. civil appeal is dismissed under the same appeal or do I need to initiate separate proceedings - MCA? Last week the District Court imposed a cost of 5,000 selectively on one of the litigants, we have grounds to believe it was an unjust cost. Today when I went to submit an application for a waiver of cost via a 10-page application outlining detailed grounds, the district court registry refused to take my application. Should I approach the high court or Supreme Court?