UK Car Repair: corsa gls l reg 1.2 mileage meter stopped, mileage meter, output shaft

Question
hi, i have a corsa gls 1.2 l reg and my mileage counter has ticked back from 81000 miles to 79924 miles and stopped. all other parts on dash works apart from this. is it possible to get it fixed as my mot is coming up in 3 months so will need it fixed, and will also need the miles put back on when it is fixed. thank you

Answer
This is an odd problem, how could the speedo reverse its-self? It can only be an electrical/electronic problem.  If everythging else is working I would suggest testing to see if the transducer, which sends the signal, is working.  I do not know your car but it is usually on the gearbox casing near the output shaft.