You probably do not know how many. Most shops find out when a customer asks, which is the wrong end of it. Partswatch is one list of every job that cannot move until something arrives, sorted by how long it has been stuck.

The part arrives and nothing happens
Ordering is not where this goes wrong. It goes wrong in the week between the box landing on the counter and somebody connecting it to the job it was for. Booking a part in puts its job straight back on the bench queue.
Every blocked job, oldest first, with who you ordered from and when they said.
Shops tell us the same thing about this screen, more or less word for word: it is not that they were ordering badly, it is that nobody could see the pile.
Questions
What does the chase email say?
Your shop's name, the order reference, the part, the date you ordered and the date they promised, and one sentence asking when it will ship. It is deliberately curt and carries no branding, because that is what a trade counter will actually read.
Can I add a supplier that is not in the list?
Yes. Type the name and it exists. There is no supplier directory to maintain and no approval step, because the list is yours and nobody else needs to agree with it.
Does the customer know we are waiting?
Yes, and it is the single most useful thing on this page. A job waiting on a part says so on the customer's own page, with the date it was ordered — so "we are still waiting on the part" is something they read rather than something you have to say on the phone.
