Dear Sir,
I am writing to express my opinion about your service. I am very disappointed with rudely treatment by your shop assistant.
According to your rule - "the customer is always right" - I am supposed to be treated with respect, but I was wromg. Your shop assistant said insulting words to me and furthermore he called me a thief. It is ridiculous. I always do shopping in your store and I have never been treated like a scump. I am thinking of changing shop.
I regret to say that but I could not say a word.
I am looking forward to receiving a satisfactory reply.
Yours sincerely,
DariO