Scottish Widows, Halifax when do accounts become "statue barred" ?

I am trying to claim money in investments made by my deceased mother (Jan 2009). I informed Scottish Widows and the Halifax in 2009 of my mother's death but did not pursue the claims then. Do I only have six years from my mum's death before the claims become "statute barred" or is it six years from when I informed Scottish Widows and the Halifax ? Or is it twelve years ? I am finding it all very confusing and worrying as I have been told that the payments will be delayed for four months due to a backlog at Scottish Widows. I would welcome any advice at all.



PS I am the sole executor and have sent grants of probate and death certificates with the claims.

Scottish Widows, Halifax when do accounts become "statue barred" ?