Gambas ONE

   Dim iDay As Integer = WeekDay(Now)
   If iDay = 6 Then iDay = -1    ' Move sat to begining of week 
   Print Date(DateAdd(Now, gb.Day, -(iDay + 1) - gb.Week))

Public Sub Button1_Click()
Dim d As Date = Date(Now)
Dim iDay As Integer = WeekDay(d)
If iDay = 6 Then iDay = -1    ' ' move Saturday 
Print d
Print DateAdd(d, gb.Day, -(iDay)  -7)
End 

Print DateAdd(Now, gb.Day, -(WeekDay(Now) + 7))