Quick answer
Separate the unresolved claim from the recurring service problem. List a few specific incidents, explain their effect and request a concrete change from someone who can authorise it. Keep the agreed next step in writing. If you are considering leaving, review your contractual commitments and alternative supply before making a threat you cannot carry out.
Decide what you want the conversation to achieve
You may need a missing credit, reliable delivery timing, fewer substitutions or a new contact route. Those are different requests. Start with the outcome that would make the next order workable, and keep old unrelated frustrations out of the opening message.
Use a brief incident list: date, order reference, problem, action already taken and current status. Three clear examples usually explain a pattern better than forwarding months of messages without context. Do not claim every delivery fails when your own records show a mixture of good and bad ones.
Send the issue to the right function
A sales representative may help coordinate, but transport controls the route and accounts issues credit documents. Ask who owns the decision rather than repeatedly asking the same person to do something they cannot approve. Keep your representative copied where useful so they can see the full picture.
A serious food-safety or product-safety issue needs prompt handling through the appropriate process; it should not wait for a routine commercial review. Preserve evidence, protect customers and involve the relevant competent people. The escalation email below is for service and commercial follow-up, not an emergency procedure.
Use a factual escalation message
Adapt the example with real references and a realistic date for a response. A date you propose is a request, not a legal deadline. Avoid stating that the supplier is liable for every consequence unless you have established that through the contract and appropriate advice.
Subject: Recurring delivery issue — action needed for account [number] Hello [name], we need help resolving [specific recurring issue]. On [date/order], [facts and current status]. On [date/order], [facts and current status]. This has meant [specific operational impact]. We have already contacted [person/team] on [dates]. Please confirm who owns this issue, the remedy for the open claim [reference], and what will change for future deliveries. Our proposed arrangement is [practical request]. Could you respond by [date] so we can plan the next order? Please confirm any agreed change in writing. Thank you.
Turn the reply into an operating agreement
Record the named owner, change and review point. “We will look into it” is an acknowledgement, not yet a plan. Ask the supplier to clarify what the receiver should do on the next delivery and which contact will respond if the problem recurs.
If you decide to change supplier, check notice, minimum commitments, equipment loans, outstanding credits and any other relevant obligations. NI Business Info advises considering the contract and continuity before ending a relationship. Obtain advice for a significant disputed exit instead of assuming a complaint email cancels the agreement.
Further reading: NI Business Info: ending supplier contracts
Check whether the change happened
Review the next relevant orders using the same facts that triggered the complaint. If the delivery window improved but the old credit is still missing, keep the credit open separately. If the supplier delivered the agreed improvement, acknowledge it and update your receiving instructions.
Retain a short history that another manager can understand. The point is not to build an archive of angry conversations. It is to reach a clear decision: continue under the improved arrangement, agree a different one or move supply in an orderly way.
Unpickle keeps quantities, notes and damage evidence together, giving the person escalating the issue a factual starting point. Use recorded delivery exceptions in the discussion.