Oh bugger, I think I've opened a resolution thingy by mistake.

[IslaValargeone]

Have not received an item bought and paid for September 9.
Went to 'contact seller' bit just to send a polite e-mail enquiring as to where my item might be.
After I did this, it said a resolution had been opened?
Have no desire to cause this seller a problem, just wanted to communicate.
What do I do now?

This happened to me too. It just does it automatically if you select item not received when you go to contact the seller. If you want you can message them to say what happened but it doesn't really matter after all you haven't received the item so at least they might sort it out now. The only way for it not to happen is to select "other" when you want to contact the seller. Don't worry they can't leave you bad feedback.

don't close it until you either have your item or money back btw.

It now seems to happen if you want to contact the seller via ebay after the estimated delivery date has been & gone. (Not sure if this is something that has changed recently or if it has always been like that.) I've had two items recently where I have done exactly the same thing as you and both were resolved.

The seller has posted me proof of postage and has asked that I close the case.
Have been to the post office there has been no delivery whilst I was out or anything like that, so what do I do.
Seller says she has done her bit?

As LilyBossom says do not close the case unless you either have the item or your money. It is the seller's responsibility to get the item to you. If it gets lost seller refunds full costs and claims from RM. Seller was a bit silly sending you the proof of postage as she will have refund you and has no way of making a claim!

Thanks, so I'll tell her I want a refund and then it's up to her to claim from the post office then.

yes do - as a seller it is her responsibility to get the item to you, she has not done her bit at all. The claim is not your concern. You just want your money back.

Yes, don't close the case until you have the item or a full refund. The seller might need the proof of postage back. I think some people think that POP certificate means they don't have any further responsibility but that is not the case which is why it is best to send anything of worth recorded.