Your frustration is understandable but you mustn't let it dictate how you react.(posted 8256 days ago)If they are sending you exactly the same letter then *they* are not making progress - which means what you had been doing up to now has worked. So keep doing it!
It might worth rereading the Do's and Don'ts pages (in the Repossession section of the site) for suggestions about how to interpret and deal with lenders - such as Abbey National - that handle requests for information like this.
Remember: if your strategy so far has reduced them to resending the same letter then their strategy is failing and your strategy is working.
It's all hard to live with but then, that's the way Abbey National and Dibb Lupton Allsop want it to be. ;-)
Lee