Hello,
Hope I can help a bit. =)
For the first item... Did you put delivery comfirmation or a tracking number on the package? If you did, check the status. If not, next time you really should. This will save and help you in the long run. This is a busy time of the year and the mail can be slower. I have had packages mail out and not arrive for 2 weeks. I always use delivery com. so I have a tracking number. Keep in contact with the customer ALWAYS because this is how you get a good reputation. Tell her you're sorry that the shipping is taking so long. Give her the shipping date, if you already haven't. It will arrive sooner or later, but always keep good customer service.
For the second item... If it was breakable, how did you package it? When shipping, always put fragile on the outer envelope. Not that it will prevent the item breaking, but it may help a little. Packages are not handled with care. Not that I am putting blame on the post office or whichever method you mailed it, but you must keep this in mind. =)
I once had a glass frame shatter for a piece going to a gallery. It scratched the painting inside and I had to drive to the gallery and fix the painting before the show opening. My fault for not using more foam and bubble wrap.
Anyways.. This is a hard one. Some artists say they are not responsible for damaged items, some say 100% satisfaction.
If it was me, I would offer to send her a new one and double package it. If she does not want a new item, then offer her a refund. I always offer this, but I require them to send me the item back.
Now if she was the one to damage it, that would not be your fault and no refund would be required.
I hope this helps. Sorry this happened to you. Learn from this and keep creating.
Julia