I am a non native speaker of english. I doubt If my following sentences are correct. I actually don't know if I should use any with singular or plural nouns in if clauses. I run a business and I want to say these to my customers. Can any english teacher or anyone who has good grasp on the language please answer this. And tell me in the given context which ones sound more natural.
- If any customers are dissatisfied with the product, they are requested to return it to the store for a full refund.
- If any customer is dissatisfied with the product, he/she is requested to return it to the store for a full refund.
- We are sorry if any customer is unhappy.
- We are sorry if any customers are unhappy.