I'm using the following code on the attached file and no borders are being changed:
Dim lo As New LoadOptions(LoadFormat.Auto)
Dim wb As New Workbook("d:\code\NationalParks\Output\1\template.xlsm")
Response.Clear()
Response.AddHeader("Content-Type", "application/vnd.ms-excel; charset=windows-1251")
Response.AddHeader("content-disposition", "attachment; filename=""" & "priority.xlsm" & """")
Dim ms As New IO.MemoryStream
Dim ws As Aspose.Cells.Worksheet = wb.Worksheets(5)
Dim s As Aspose.Cells.Style = ws.Cells("C6").GetStyle
s.Borders.SetColor(System.Drawing.Color.Aquamarine)
s.Borders.SetStyle(CellBorderType.Thick)
ws.Cells("C6").SetStyle(s)
wb.Save(ms, SaveFormat.Xlsm)
Response.BinaryWrite(ms.ToArray())
Response.End()