when i remove key from ignition my 2008 tdi passat keeps on running and shows handbrake fault

There is a relay above the fuse box, that relay needs to be replaced. It is a small green at the top. Do that and the problem will be over.

Joseph, which relay are you referring to?

My 2002 keeps running when I turn car off and remove key from the ignition. I have to press the brake to cut the car off, the inside lights just randomly come in and continuously run my battery down. Could the problem be a relay?

Your interior lights issue is due to a faulty doorswitch. When you open each door there will be a switch on the vehicle frame that interacts with the side of the door and opens or closes the lighting power circuit to ground. One or more of these switches are bad. You can easily remove them yourself in about 5-10 minutes each and test them with a digital multimeter., or a few wires and any 12V battery or power source. In any case, they should cost between $2-5 each at the most and I'd just replace them all to save yourself the hassle. In the meantime you can turn off the interior lights from the overhead dome light. Just be sure to make sure that the new switches are well lubricated before installing them to prolong their life and the metal contacts inside. This is a very common problem on most vehicles, but a simple and cheap fix. As for the car ignition running, that could be any one or more of a long list of items to check.