Arek Milik admits no-one from the club warned him Napoli would be leaving him off their squads for Serie A and Europe.
The Poland international revealed he learned about the decision in the newspapers.
“I heard it from the press. I expected this decision but the lack of communication from the club is not professional," Milik said. “I believe I haven't been treated well.
“There are other players who didn't renew but for them everything is calm. I have been the leading goalscorer of the team in the last two seasons and I have always given 100 per cent.
“I have no regrets for what I have done and what I have decided. I will suffer a little, but I will resist."