Die-Acetyl

'Lo all,
Been brewing for near on a year and have run into my first issue (aside from a home-made lauter tun manifold that required fine-tuning) - diacetyl in my lager. I thought I had conformed to the rules; cleanliness, a diacetyl rest and adequate pitching, but I've now got some nasty lager. My first lager was made in winter, so was easy to temp control but this one was in a fridge. I rested it at ~65 for three days and it tasted fine at bottling two weeks ago (neither of the other two batches that got bottled that day have any signs of infection/contamination), so I wondered if anyone had any suggestions about what I could do in the future to avoid months of hard work going into the butter dish. It looks beautiful too, is there any hope for it?
Thanks in advance

Sounds like you already know this, but pitching enough yeast at or a few degrees below fermentation temps, and then a d rest ~75-80% through fermentation is the best way to avoid a butter bomb. I've never done it, but I've heard that the 'pitch warm then lower' method is hit or miss. With lager, I pitch at ferment temps and if anything over pitch slightly. I do a d rest + ~10 degrees from ferment temps for the final ~20% or so of fermentation and then slowly lower to lagering temps over a few days. Works well for me, YMMV.