Anonymous“We collected a cake from the pier shop on last week. However, the cake's bottom layer was broke. Your colleague refused exchange the other one for us and advised that this is no problem. Would you please invertage / double-check for such case and how can we protect our rights and interests in such case? Please advise.
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There are several problems with this paragraph.
Why "collected"? What is a "pier shop"? "Invertage" is not an English word. Here are some possible corrections:
"We bought a cake from the shop last week. However, the cake's bottom layer was broken. Your colleague refused to exchange it and said it was not a problem."
I don't know what to do with the rest because I'm not sure what you are asking for. "How can we protect our rights and interests in such case" seems very dramatic when the subject is a broken cake. Are you asking for a refund? An apology? A new cake? An assurance that such a thing will not happen again? Please try re-wording the last part to make your meaning more clear.