As I said before, we are in a similar situation. His visa is valid from 16/08/11 to 16/11/13 and it says visa to acc parent. (passport expiry 2015)
We wrote to the UKBA the 6th December explaining the situation and enclosed photocopies of their passports and visas.
We received a reply on the 20th December, it says
“A correction to an error on an entry clearance visa will be carried out free of charge by the UK Border Agency if the migrant has already arrived in the UK.
There are two ways in which the migrant can arrange for the correction to be made
They can either:
Write to the Entry Clearance Manager at the relevant post with full details of their application. If the diplomatic post acknowledges that there has been an error, they will write to the migrant asking them to submit his/her passport, two photographs (name on the back).
Alternatively, the migrant can write directly to the relevant address explaining the error and enclosing passport and two photographs (name on the back)
Enquires will then be made to the Entry Clearance post by the casework team in order to confirm if an error has been made.”
The address given is the same Joe has given in his earlier post.
We decided to go with the second option and send his passport to them straight away.
We received a further letter this week asking for us to send the two passport photographs to them so they can make their decision; unfortunately we forgot to send these at the same time as we sent his passport.
So now we wait again to see if they will change his visa.
As Joe has suggested, write to them to explain your situation, goodluck