Dh and DSil went in together on a mortgage to buy our first home. DSil already has a mortgage. Mortgage advisor (at J&C) advised them to go with nationwide first time buyer £500 cashback mortgage, even though dsil was already mortgaged. Called mortgage advisor the other day to see when we'd be getting the cashback as we've now been in our home 2+ months. He said he'd look into it and call me back. When he called back he told me nationwide had declined the cashback as Dsil already has a mortgage, but the mortgage advisor already knew this when he advised them to go for this mortgage! Have we been mis-sold our mortgage, and if so what do we do now??