Depending on the exact make and model of your vehicle, the VIN is usually printed in more than one location on the vehicle - a quick Internet search should tell you where to look. You can then check this against the information printed on the V5C registration document. If these do not match it could be that the DVLA has the incorrect information and it may be as simple as informing them, but you may also wish to pay for a vehicle history check to establish the true information attached to the registration plate.