How did you go about handing it back to the dealership? I would prefer to do this as my local VW dealer is right across from the BMW dealer.
I think your best bet is asking your new dealer if BCA can collect it from them. BCA can collect from anywhere. I have timeline my most recent VT last month below...
Aug 24th - Confirmed car collection date of Sept 1st. Agreed with dealer to leave my current car with them.
Aug 25th - Rang VWFS to VT, was asked to provide current mileage and some basic questions about service history and do I still have V5.
Aug 27th - Letter confirming VT with shortfall to pay invoice.
Aug 28th - Phone call from BCA wanting to know where to inspect the car and where to collect. Collection would be day after inspection. As it was going to be at a dealership they asked for the sales persons name and telephone number.
Sept 1st - Collected new car and left old one at dealership in their compound. Dealer did a basic check and I took photos, inc odometer.
Sept 3rd - Text from BCA to say inspection was 11th and collection 12th from Dealership address.
Sept 15th - Letter from VWFS with excess mileage and cleaning charge, with 30 days to pay.
Sept 16th - Paid in full.
I would say that I did get no communication from BCA once the car was collected. I have also had no word from VWFS to say I have settled the account. This was the case on the car I also VT'd in May. Also worth noting nothing other than "account settled in full" shows on credit file.
Hope it helps.