I have an unusual mileage question. About a year ago I sold a larger number of airline miles to a Jewish broker, who paid me at the time. I now noticed a year later that they're still in the account. I thought that maybe I didn't really sell them, and that if I did and he forgot about them, it's an issue of ta'us Yisrael, so I called to clarify. The Jewish broker said that I did sell the miles to them, and they resold them to a non-Jewish broker, who paid them in full.
I asked how long do I have to keep the miles and password intact for, and if at a certain point I can assume they were forgotten about, or that it's a ta'us akum. The Jewish broker doesn't want to jeopardize his relationship with either side, so he told me to wait another year and then call him back if they're still there.
I realize that ethically I could be nice and bring the mistake to their attention, but I first want to know what my obligations/rights are. What is the status of these miles, both legally and halachically? Who owns them now/1 year from now/10 years from now? Is there a point at which I can assume they were forgotten about and use them? If so, does that point depend on what I'm told by the Jewish broker I sold them to, meaning could they be mine now even though he didn't want me to use them, or could they not be mine in a year even if he tells me at that point I can have them? And does it make a difference if the Jewish broker said that the place he sold them to has since changed management?
Also, independent of the miles themselves, how long do I have to keep the temporary password on the account? Even if the miles aren't mine, is there a problem at this point to switch the password, and if the miles are remembered and they can't access the account, they can come to me at that point?