Returns and replacements are handled by the shop that took your order. This page explains the practical side for foam, which behaves differently from most parcels.
Open the order on the shop you bought from and use its own returns flow. It holds the payment, the carrier record and the stock, so it is the only place that can issue a refund or send a replacement tube.
Half an inch of length either way is normal, because foam is cut on a line. A faint seam along the tube is the extrusion mark. Colour varies a shade between production runs, so a replacement noodle in a mixed pack may not match exactly.
A split skin, a crushed section that does not recover, a missing tube from a sealed pack, or a slit in a clamp noodle that runs right through the wall. Those are worth reporting straight away.
Foam that has been in water is sometimes excluded from a standard return window. Check the listing's own terms before you swim with a tube you are unsure about.
