Returning a part to a supplier Wrong item, faulty on arrival, or ordered in error — how to record the return so the job and the invoice both stay honest.
Pricing a part you fitted Cost price, your margin, and where each of them is set — so the total the customer sees is right without anybody doing arithmetic.
When a part is never going to arrive Cancel the line, tell the customer honestly, and decide between an alternative, a refund or returning it unrepaired.
Booking a part in when it arrives Mark it received against the order line, and the job it was blocking goes back on the bench queue by itself.
Chasing a part Put a job on Partswatch, tell it who you ordered from and when they promised, and let it do the chasing.