We deal with tracking numbers all the time, shipping worldwide. Fortunately, missing or delayed deliveries are rare. But whenever they happen, and because we are the shipper, we chase missing or delayed items on behalf of our customers and keep them up to date with all and any information that we have. After all, we are responsible in that we have taken money from the customer, and it is therefore incumbent on us to safeguard the rights of the customer. This philosophy has served us extremely well, and we are very very proud of our customer service, and that is shown in our 100% feedback.
Having said all that, the service you are getting from your supplier frankly stinks!
You have a couple of actions to take. First, report the supplier to Etsy as I believe they are in breach of Etsy ethics. Secondly, you leave appropriate negative feedback, and send a personal message to them explaining the reasons for negative feedback, and also informing them that you will never darken their doorstep again.
Harsh, I know, but this shop needs a wake up call.
Just my tuppenceworth.