VBA Code to Total Sections with Varying Number of Rows

This is weird ... I posted an updated code yesterday but it disappeared Anyway, try below code

Sub test()

Dim a, Col$

With Sheets("BOM")
   With .Range("C1", .Range("C" & Rows.Count).End(3))
      a = Filter(.Parent.Evaluate(Replace("transpose(if(isnumber(search(""rental"",@)),false,iferror(if(search(""section"",@)>0,row(@)),false)))", "@", .Address)), False, 0)
      If UBound(a) = -1 Then Exit Sub
      ReDim Preserve a(0 To UBound(a) + 1)
      a(UBound(a)) = .Rows.Count
   End With
   For x = 0 To UBound(a) - 1
      For i = 1 To 4
         Col = Choose(i, "G", "I", "K", "N")
         .Cells(a(x), Col) = "=sum(" & Col & a(x) + 1 & ":" & Col & a(x + 1) - 1 & ")"
      Next
   Next
End With

End Sub