Dont know if this is of any help for you but I worked in NW lending until recently.

First thing to do is to ring NW via the telephone banking team and ask for a borrowing review. You will be put through to one of two places. If you go through to the telephone advisors then theres a good chance that they will be able to lump everything in together for you and keep your payments under control (this is decided on an internal credit rating) if not (or you are put through to customer lending) then the bank will offer you a consolidation loan for your debts with NW. Essentially your current loan and overdraft will be lumped together and (hopefully) result in lower payments.

With a £1700 OD you will be paying around £25 a month in interest alone! (NW od rate is 17.9%) if you can get it lumped into the loan it will end up costing a whole heap less!