Pictures would help but it definitely sounds fake. The 10124 number is a valid Coach-style serial number and it should be INSIDE the bag when the C pattern is on the outside, but I've seen plenty of fakes where the whole design of the bag is wrong. Yours sounds like one of those fake Signature Stripe Totes. The number you say is on the inside is a complete fake and would never have been used by Coach, but I've seen a lot of fake bags with similar numbers. If you bought it off someone on Craigslist, I hope you didn't pay cash for it. There may still be a chance that you can get your money back if it's a recent purchase and if you used Paypal or a credit card.