From "that other place":
Assuming you are exactly half way through and the amount you have paid thus far is just "normal" repayments ( no Overtime etc), you still have 7800 to pay off to make your projected 23p in the pound. So your calculations above are flawed, I am afraid, as making an offer of the full £7800 will still only net 23p/£.
Considering you would be paying the lump earlier than the 60 month end date the creditors might agree to "losing" a little, but not a lot. Looking at it from their point of view, unless you have compleeing reasons to end early, they might as well sit back and get more money out of you!
Personally, and I may be wrong, I think you'd be pushing your luck with an offer of £6000, might get £7000 accepted, but not £4000. Sorry.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014
