not received item, sent email when do I open a case

[SodaStreamy]

I've waiting 9 working days so 2 beyond the expected arrival time and no sign of item. Item is not marked as dispatched

I've emailed buyer but not heard anything.

How long should I leave it before opening a case, I don't want to create unnecessary problems for the seller if it's an oversight.

It's only £3 in total so no real urgency I suppose

open it now - you have waited plenty of time.

thanks

I've not had to this before so am unsure what to do. Could you talk me through it? I assume I do it in ebay and not paypal?

here you go - item not received

res.ebay.co.uk/ws/eBayISAPI.dll?ResolutionCenter&_trksid=p3984.m2295.l3923