Crossing the line

This is a new carpet that my mother has just had put down in her lounge. This is now the second carpet she has had to get, because the previous carpet had a fault in it.

When this was put down, she said to the fitter

"Isn't there a huge line running along it?"

"Aye, that's a pole mark, it'll go pretty qucick, after a few hoovers"

100 hoovers later and the line is still very much there, and my mother is being fobbed off by a major department store.

Your views on this would be welcome - can you see the obvious line?