Package I sent has fallen apart in the post - What do I do?

[NoTwinkies]

I sent 3 items together in a package. The seller has just notified me that one is missing and the other 2 turned up in a royal mail bag with the 'flimsy' packaging. Should I take this up with the Post Office? Or refund buyers postage costs/total costs?

It depends how you packaged it up, sounds like it wasn't Royal Mail proof! We've had parcels arrive in pretty shocking condition, not the sellers fault but if you've seen the state of some things then you add an extra layer of bubble wrap and tape.
I would refund if the items are lost or damaged.

Yeh I think you're right should have used more tape.. Do you think a refund of the item cost and the price I added for packaging would be ok? I'm not sure of protocol but I did send it so I can't really refund the postage costs.. or is that what I'm supposed to do?