The past is not an indication of the future. Yes, you have the right to get some information about the past performance, but not what your performance could be in future. I understand that's the main issue here.
Apologies if I got this wrong, but I have seen too many of those threads where people complain because a vendor did not promise them something he really could not. No vendor can promise you anything in terms of future performance, for instance. At least, not in good faith. At best, to get your money.