The buyer has kept emailing me with any issue she or he(i will say he from now) could right after 3 days from he purchased.

First, he supposed to ask me about the shipping time and the tracking information simply after he had purchased. but it wasn't simple at all, he said that he expected the item to be delivered in 1 week from shipping according to his email. it was a bit suspicious already, but i tried with my best.

Then, he emailed me again and said the item hadn't arrived yet and asked me checking the tracking information.
It was already arrived when i checked and let him know about it.

Today, he emailed me and told me that he wasn't satisfied with the item because there was something missing which is not included originally with the item at all(it is noticed in the detail page anyhow).
he said that he hasn't leave a score(which is feedback) to me yet, and asked me he doesn't know what he can do...

what is it?
i checked his feedback to the other sellers.. guess what? he left negative a lot to them...

I will report him ebay too.