Sarkis, it is one of the common mistakes they make. I have had that problem multiple times. Most of the time, they just forget to check those items in. So, go and check for those DVD's in the library and if you find then, let the them know about it. If it is not in the library tell them that you are 100% certain that you have returned the DVD's and talk to the library manage if need be. Normally, you would not have to pay for the DVD's because it is not your fault..