To be honest, I think Start knew we were looking into switching our Mortgage in Feb/March (they could see that other banks were checking our credit history on the ICB and I was requseting our mortgage statement). If the DD was cancelled with them they had no reason try and get the money form PTSB. I would not be supprised if they were trying to sabotage our chances of remortgaging.
Our ICB hasn't got any black marks because of this, but Start have refused to take the "Late" reference off our statement which is the reason why we were refused a remortgage (apparently just by having any reference to late payments is enough to refuse). Start have sent us a letter, after hours of discussion on the phone, saying "due to a technical error in March 2007 we applied for payment with the wrong Direct Debit details". Hopefully this will be enough to successfully switch our mortgage!!