In reply to Fellover:
We had the same problem with a canoe trailer in Germany.
The wheel fell off while on route south, phoned recovery and the understanding was it would make its way back to the UK, we couldn't fit all the boats in the towing vehicles so left a £1800 boat strapped on the trailer as it would make its way back to the UK.
Long story short the recovery company decided it was not worth getting it back to the UK so offered us a setlment amount for the value of the trailer not the boat that was strapped to it as well.
We ended up taking a flatbed trailer out to mid Germany to recover the thing ourself.
UK breakdown service does seem hit and miss about getting your car back to the UK due to the cost involved, they will also drop you at the port then the UK recovery will need to drag you on to the ferry or the French will drag the car onto the ferry and leave it at that.
Good luck.