It was one of the more thinner tubes, I have emailed the seller, What a tosser. He won't except responsibility for any thing, saying it's the Royal Mails fault and he's in the clear...
Bad seller all the way.
Responsibility of the packaging should always remain with the seller in my opinion.
However, what happens to the package in transit is the responsibility of the postal service involved.
I would never send a poster in such a thin tube, but if I did and that happened I would return the cost of P&P in full and give a partial refund or ask for the posters to be returned to me with a full refund given.
But like I say, I would never use such a flimsy tube.
I once had hundreds of tubes, but binned 90% of them because they were terrible; no joke, I could crush some of them using my little finger and thumb!
Hope you get sorted, Paul!