The broker has leased the vehicle from VW for a certain price a month. As part of that agreement, if they get to the end of the lease, the vehicle is not theirs i.e. they have to return it.
As part of the lease agreement, there's an option to cancel it and pay off what is owed, and give the vehicle back. This is a B2B deal so nice stuff like consumer credit act doesn't apply.
At the end of the lease, the vehicle will get re-sold by the dealer used by the broker, but it has to be sold on to someone other than the broker themselves. It is also possible for the broker to sell the vehicle on behalf of the dealer and pass the cash on to the dealer in full.
(I believe that you cannot sell directly to the person who took the lease as it's seen as a way of avoiding VAT by HMRC, which is effectively how the broker is able to get such good prices!)
I imagine that there is a limit to the number of vehicles a broker can lease/sell on, and once they pass that limit, the finance company start digging in and refusing to allow any more to be sold.
While the vehicle is still leased by the broker (3-6 months after delivery) it's legally owned by the finance company. Only when the broker does an early termination and settles the finance bill does the ownership transfer to the third party, and the V5C get released.
In this instance I imagine the broker has tried to terminate the lease agreement, has been investigated, and the entire lease portfolio for the broker has been terminated by the finance company. Ownership remains with them, so they may be who you need to speak to regarding the re-purchase of the vehicle now...