purchased my cls from main dealer,it had covered 23 miles since it's last mot,paid £185 road tax and waited 3 weeks for the v5 to arrive.i then tried to assign my number plate on line,refused.rang up Swansea to be informed that as the car had been untaxed for a period of time I would have to send my v5 and v750 to them,approx wait 2-4 weeks for my new v5 to arrive and I may have to have my car checked at an approved mot centre.what a waste of time and money as they already had the relevant docs.as all remaining tax is now returned to the previous owner the car must be untaxed therefore this must be a problem to anyone wishing to change number plates (rant over)