airtable automation for recurring task for weekly, daily, monthly, 3 times per week and twice a mont

[Sakshigupta]

Hi ,I am creating an airtable automation for recurring task for weekly, daily, monthly, 3 times per week and twice a month  In the next to perform date i used this formula DATEADD({Due Date},SWITCH(Frequency,'DAILY',1,'WEEKLY',7,'MONTHLY',30,'TWICE A MONTH',15,'3 TIMES PER WEEK',3),'days') It works perfectly well for daily, weekly and monthly, twice a month but it doesn't work for  3 times per week i need (Monday, Thursday and Sunday)
can you please help me with the formula?