Trust Deed & Max Recovery?

I went into a trust deed under Scots law 20 months ago. We had a joint debt (A Together Mortgage) with Northern Rock We repaid the mortgage,but not the unsecured element. Basically, due to mess -ups on both sides, NR eventually sued my partner for the whole debt, and have also claimed the whole debt against my trust deed. My partner, who is not bankrupt and still has a credit rating, has been paying this debt for several months by Direct Debit. Lo and behold, six weeks ago he gets the 'Max Recovery - do not reply' letter.The Direct Debit from our bank was stopped by Northern Rock. When we eventually managed to talk to someone at Northern Rock he said this had been a mistake. Now NR are saying the debt has been sold on and have not been returning our phone calls. MAX recovery havent asked my partner for any payments towards the debt. Is it worth trying to get in touch with this MAX recovery lot, as we couldnt face another trail to courts etc.We are trying to ensure that we bank the money each month in case they come back to us, but as it was quite a struggle to afford the payments in the first place, it is only to easy to dip into it - especially at Xmas!