1st, contact DVLA at Swansea & explain your problem, there is no excuse for the delay in the information Re/ Road Tax, you could have contacted DVLA as soon as you knew the Log Book was missing or lost they will have issued you with a replacement, Regards the Tax And the over due payments If you can prove the car was off the Highway for the time you stated they may not demand Back tax, ask the Garage that done the repairs for written confirmation of the dates your car/ Reg was off the road.