Try fitting the thinnest felt back on 11 mm underlay then as i have as according to Carpetright it's not a problem lol. It's like laying a blanket over a sheet of foam then walking over it lol
Which in most cases is pretty standard, certainly with carpet. They see new fluff and say lovely, regardless of power stretched, normal stretch, stairs from bottom or top, tight or saggy. They don't really have any idea of a god job.
