Bluebird, if I were in your shoes I'd hang on to all your paperwork. You can bet your bottom dollar that you'll be kicking your own bum if you bung it in the bin. It's like gold dust. Look after it, stash it under your pillow or something, treat it like a good woman, because you can guarantee you're gonna need it some day!
AndyGH, if you're earwigging, you might heed what Malc' F is saying. One of FLJ's NDP6060L's would indeed do the trick. It's pin-for-pin compatible with your BUZ11, albeit with a slightly superior specification, so all you have to do is pop it into place on the PCB (assuming, of course, you remember which way round the metal tab should be facing).
And welcome to the "We-love-ZN409's" club.