I had success in claiming back Abbey charges on our mortgage last year (I still have my mortgage with them today)
I did the
SAR
and got my figures together etc.. used spreadsheet in CAG to lay out what I was reclaiming and it automatically added in the 8%
interest
for me.
Then I used the Pre Lim letter as like claiming back bank charges - just edited to suit mortgage account number etc.. (gave them 14 days)
Abbey Wrote back telling me I was nuts - it was only bank charges I could reclaim (LOL how daft do they think we caggers are?

)
I followed this up with the
letter before action
which gave them another 14 days and enclosed the spreadsheet again showing them what I wanted back off them. Abbey chose to ignore me.
So I copied both my letters, spreadsheet of charges and Abbey's reply to me and I completed the
fos
complaint form and sent it to FOS to ask them to look at it.
FOS got ALL my money back and including interest. It takes a little time cause FOS are so busy BUT it was easier than court route for me cause it meant no fees, no risk of costs if I lost etc.. FOS dealt with it all for me.
I asked for all the late payment fees, admin charges, their counsellor fees (they always sent a man knocking door when in difficulties) - I got all of it back no arguments.
Companies don't want FOS to investigate them - it costs them money etc.. so they pay up to avoid investigations
If we go court route Abbey (like any other company) will try confuse and use scare tactics to put people off reclaiming - they are so wriggley and there is always the threats of costs etc.. if a case is lost in court. So I think FOS route is worth trying because the worse that can happen is FOS will investigate to find you were wrong? No costs involved BUT if in court you find you wrong and lose consequences are likely to be high legal costs.
You are entitled to reclaim charges on your mortgage whether or not your mortgage is still with Abbey. I am sure time span is 12 years you can go back rather than the
6 years
with Bank charges.
Good Luck!!