Approval feels like the finish line. The provider has agreed to pay, the shop has the go-ahead, and you assume the car will be fixed soon. The contract may treat approval as a middle step. Between the approval and the fitted part there is usually an order, a supplier, a shipping date, and a receiving check, and each of those can be written loosely or not at all.
Find out who orders the part
Ask whether the shop orders the part, the provider orders it, or a third party does. The contract should say which, because the answer tells you who to call when the order stalls. If the shop orders it, the provider may still need to approve a substitute. If the provider orders it, the shop waits on someone you may never speak to. Get the name of the party holding the order before the car goes on the lift.
Read the part description
Contracts describe parts in different ways. Some refer to new parts, some to remanufactured or rebuilt parts, and some to parts of equal quality or function. Some name a manufacturer and some do not. Read the sentence that defines the part, then compare it with what the shop says it will install. If the two descriptions differ, the difference belongs in writing before the work starts, not as a surprise at pickup.
Ask what happens when the part is not in stock
A part can be on backorder, discontinued, or shipped from a distant warehouse. Ask whether the contract allows a substitute, who approves the substitute, and whether the substitute falls under the same approval. Also ask how long the provider allows for a delayed order and what the shop should do if the wait runs past that window. A vague answer here usually means the wait is open ended, and an open ended wait is the hardest kind to recover from.
Check the fitting and the removed part
Some shops and providers keep the removed part for inspection, and some ask the owner to hold it for a period. Ask whether the old part must be returned, whether the provider requests it, and who handles disposal. Ask too whether the shop will record the installed part by its part number or serial record, since that record is what a later question will turn on.
Keep a parts file
Write down the order date, the part description, the supplier, the expected delivery, and the name of the person you spoke with at each step. Keep the invoice and the receiving record with your contract copy. If the part arrives different from what was approved, or the shop installs something you did not authorize, the file lets you show the sequence. Do not rely on memory, and do not rely on a verbal promise that the contract does not repeat.
What to check before you sign
Look for the parts clause in the contract itself, not only in the brochure. Find the definition of an approved part, the rule for substitutes, the time allowed for delayed orders, and the rule on removed parts. If any of these are missing, ask the provider to put the answer in writing before you commit. Providers that post their contracts make this easy to test, so start with the list of companies that publish a sample contract you can read first. The methodology page explains how this site reads contract terms, and the published figures on the main ranking show how each company's terms are set out.