When i bought my motorhome new from a local dealer it was plated at 3,850kg but the dealer had registered it as 3,500kg on the V5.
12 months VED was included in the sale so i only noticed the mistake when it became time to renew the VED 12 months later when the rate was higher than expected.
The DVLA couldn`t / wouldn`t sort it straight away so i had to pay the higher rate so i could still use it until it was eventually sorted nearly 6 months down the line.
Back then the DVLA still had offices and we had one in Preston and even though i thought i`d sorted it twice when the V5 came back from Swansea it was still wrong.
I eventually blocked the car park with it at the offices here in Preston and that soon got a response with security and then a senior manager.
I never did get an apology and at one point was told it was my fault and i was liable to prosecution for not ensuring the DVLA had the correct info about the vehicle.
It took a further 12 months to get a refund for the excess VED i`d paid, so all in it took 18 months from start to finish.