在日常生活中，我们难免会遇到一些不如意的事情，比如产品质量问题、服务态度不佳等。在这种情况下，写一封礼貌而有效的投诉信就显得尤为重要。下面是一些适用于英语投诉信的万能句型，帮助你更好地表达自己的诉求。

1. I am writing to express my dissatisfaction with the product/service I received.

2. I would like to bring your attention to an issue regarding my recent purchase.

3. I recently purchased your product/service, but unfortunately, it did not meet my expectations.

4. I am writing to complain about the service I received on [date].

5. I have encountered a problem with the product/service I bought from you.

6. It is with regret that I must inform you of my disappointment with your company's service.

7. I am writing to report an incident that occurred during my visit to your store.

8. The quality of the product I received is far below what I expected.

9. I am writing to request a refund for the item I purchased.

10. I believe there has been a misunderstanding regarding my order.

11. I am writing to seek clarification regarding the billing statement I received.

12. I am writing to request a replacement for the defective item I received.

13. I am writing to express my concerns about the delay in delivering my order.

14. I am writing to ask for an explanation regarding the charges on my account.

15. I am writing to request compensation for the inconvenience caused by your service.

16. I am writing to register a complaint about the poor customer service I experienced.

17. I am writing to request an apology for the mishandling of my order.

18. I am writing to request a solution to the problem I encountered.

19. I am writing to request a follow-up on the status of my complaint.

20. I am writing to request a refund due to the breach of warranty.

21. I am writing to request a credit for the inconvenience caused.

22. I am writing to request a resolution to the issue I reported.

23. I am writing to request a review of the charges on my bill.

24. I am writing to request a modification of the terms of my contract.

25. I am writing to request a termination of my subscription.

26. I am writing to request a revision of the invoice I received.

27. I am writing to request a correction of the errors in my account.

28. I am writing to request a review of the decision made regarding my complaint.

29. I am writing to request a settlement of the dispute between us.

30. I am writing to request a review of the policy related to my issue.

31. I am writing to request a clarification of the terms and conditions.

32. I am writing to request a review of the procedures followed.

33. I am writing to request a revision of the agreement.

34. I am writing to request a resolution of the conflict.

35. I am writing to request a review of the decision made.

36. I am writing to request a settlement of the matter.

37. I am writing to request a review of the process followed.

38. I am writing to request a revision of the terms.

39. I am writing to request a resolution of the disagreement.

40. I am writing to request a review of the action taken.

以上这些句型可以帮助你在撰写投诉信时更加得心应手，无论是表达不满还是提出解决方案，都能做到条理清晰、逻辑严谨。希望这些建议对你有所帮助！