Scam - USB memory stick

Recently it has come to my attention that a scam is being operated high end USB memory sticks. The seller reprogrammes a 2gb memory stick to look like a 16gb or 32gb. The buyer gets the stick may take quite a while to fill it up beyond the 2gb by which time the buyer has left ve feedback. If you notice (I did) the seller immediately offers your money back so you do not give -ve feedback. The only way to check the size of the stick is to try filling it up. I have contacted 3 people who gave ve feedback from what looked like good sellers, all of whom found that they had been sold small sized memory mascerading as 16gb or 32gb! I suggest that you check any USB memory stick that you buy before you give feedback!