item won 3 weeks ago - still not arrived - what should I do?

[EccentricaGallumbits]

Won something 3 weeks ago - only 99p. Paid straight away by Paypal. I've sent a couple of messages asking if it has been posted but seller ahsn't replied.
What do I do next? How long do I wait for?

iirc you have something like 35 days to file item not received

as the seller isn't replying I'd do that now