I think you need to kick some arses! If they told you you would have a hire car today I think you are within your rights to say you will be hiring a car yourself and expect VW to pick up the cost until the car they are supposed to be providing you has arrived.
Also their idea of what constitutes a build week has evolved as far as I can see along these lines:
1. BW = Fully build within that week
2. BW = Started build within that week, might finish next week
3. BW = Built in this week, or in the following week
4. BW = Might still not be build over two weeks later
I'd be pressing very hard for an answer from them on when it will be done and WHY the delay. No BS. Personally I didn't believe a word they told me and I am 100% convinced they are just spinning crap in order to fob you guys off long enough so that the cars arrive and their problem (angry people calling) goes away. I'm not sure if this strategy of fob off excuses is intentional or if it is merely a by product of their lack of information and their inclination to be wildly optimistic and assume the best case all the time.
Interestingly I was telling my Dad about this constant changing of excuses the other day and he related to me something that happened when he was the foreman at an engineering firm that made marine and power equipment. He is sitting next to the production manager who gets a call from an irate customer who has a bunch of marine tugs or some sh!t that are awaiting parts from this company and the parts are late.
The production manager explains, in a cool manner, exactly what the problem is. He has these parts and has been dealing with them personally and is doing all he can. Problem is there is some machine that is broken and they require some other parts and then x and y must happen and so on and so forth and the customer is sure to get his parts delivered by such and such a date. The explanation takes 10 minutes it is so involved and detailed.
The conversation ends and my Dad turns to the production manager and says "give me the part numbers, I'll go down there now and get this sorted". The production manager says not to bother as everything he said to the customer was made up to just get them off the phone and buy more time to deliver the parts.
Now I don't know if that is what VW are doing, but they've given me no reason to believe its not what they are doing!