lo que yo hago es seleccionar el rango de las celdas, luego quitarles el borde (por si lo tienen asi que lo limpio) y luego dar la linea de abajo... Termino limpiando las lineas que no ocupo
Código:
Range("C6:E15").Select
Selection.Borders(xlDiagonalDown).LineStyle = xlNone
Selection.Borders(xlDiagonalUp).LineStyle = xlNone
Selection.Borders(xlEdgeLeft).LineStyle = xlNone
Selection.Borders(xlEdgeTop).LineStyle = xlNone
With Selection.Borders(xlEdgeBottom)
.LineStyle = xlContinuous
.Weight = xlThin
.ColorIndex = xlAutomatic
End With
Selection.Borders(xlEdgeRight).LineStyle = xlNone
Selection.Borders(xlInsideVertical).LineStyle = xlNone
Selection.Borders(xlInsideHorizontal).LineStyle = xlNone