You need to open a case for item not as described from the Resolution Centre, link at foot of most pages.
That enforces the seller to pay for any return tracked postage.
Escalate on days 9 - 21 if not refunded beforehand.
Never close the case early, on any excuse or promse from the seller, once closed, it cannot be reopened. Let it run the full 8 days, and if not resolved in that time, do not forget to escalate.
