Kate,(posted 8279 days ago)My understanding (and experience of other people's letters) is that lenders often tell ex-borrowres, 'give us discounted sum X or we'll come after you using court channels for the full sum Y'.
If you can afford the extra tenner, then yes, I would certainly serve a SARN on the lender's agent. I did, and came up witth some useful additional data.
No, I don't think lenders and their agents are 'prepared to negotiate' in any sense that you understand it. I think that they want to take you for every penny they can get, as cheaply as possible, for very little effort, and without having to substantiate the claim reasonably or properly. Read this site for details, especially under 'Repossession'.
If this is a claim against your husband, and not you, make sure that the lender does not coerce you into divulging data about you and/or your two children. Tell the Information Commissioner if this is going on, or appears to be going on, please.