CRELoaded/OSCommerce Database customer info problem

I currently have an CRELoaded website that has been giving me serious problems. Customers will make an account and then when they check out their address/email/and sometimes names will be switched with another customers. So when they check out either the order goes to the wrong address, a confirmation email goes to someone how didn't order anything and so on. If they stick items in their wish list when they come back to check it out there are totally different items that they never put in there. I've paid 2 people to try and fix this problem and they say the sites code and everything is perfect so it has to be a Database problem. This could be a serious security/privacy risk and I need someone how has .php experience along with SQL experience. NOTE: PLEASE BE AWARE THAT YOU WILL NOT BE PAID IF THIS PROBLEM ISN'T FIXED. Once you say it is fixed I will escrow the funds but I will not release them until I am 100% sure its been taken care off. Thanks.