The way to explain that is via an analogy. A web site is sort of like an automated cash register. Suppose you bought something in a retail store and when you paid for it, the cashier used a cash register made by the electronics firm Sharp. If you had trouble with the purchase, would you then approach Sharp? Sir, we are like Sharp in this situation. We made the internet version of the "cash register": the web site software which allows the vendor to operate. That software has our name on it and a link to our web site, the same way that a cash register made by Sharp has the Sharp logo. Even though your cash went into a register with the Sharp logo on it doesn't mean you were doing business with Sharp.