Once we have agreed to send you a part, it is handled as its own small shipment rather than as a new order. Here is the sequence, so you know what to watch for.
We confirm it on your existing thread. Whatever channel you reported the problem on, the confirmation and everything after it stays on that same conversation.
It is packed and sent. Occasionally a part has to wait until it is back in stock, and if that happens we will tell you on the thread.
You get an email with tracking when it goes out. That email carries the tracking number and the link to follow it, which is the fastest way to see where the part is. It may arrive separately from any other parcel of yours.
If the tracking number will not pull anything up, give it a day: a number is usually issued when the label is created, and it often shows nothing until the parcel is physically scanned into the network. Use the link in the dispatch email rather than typing the number into a search engine, since that link points at the right carrier for your parcel.
If it has gone quiet, reply on the same thread with your order number and we will check where the part is and come back to you. There is no separate order number for a replacement, so your original order number is the thing that lets us find it.
Reporting a fault in the first place, and what is free versus charged, is covered in What do I do if my device is defective? and Do your kits have a warranty?