Illegal goods ?!

I could with my Apple ID does not register when I cloud and had called and told that my purchased phone should no longer be on sale and has been disabled by Apple on at Apple. I was offered to activate the cell phone again, if I can show the corresponding invoice. But I have been sent no bill. Amazon takes the phone back now and I get my money back - but with the recommendation it "easy to try again," what will I not make sure.