I am currently using SharePoint O365 custom list with a New Responsive Form. I am looking for a way to utilize my calculated column to calculate the difference between two dates, but to exclude Sundays from that calculation (as these are considered exception dates). I also need to be able to reflect the difference on my form as well.

Column Calculation so far: ==Completion Date]--Received Date]

Form Variable Formula so far:  dateDiff("totaldays",sForm].mReceived Date],eForm].mCompletion Date])