My experience with DF was good for a couple of years, and when things went wrong they acted reasonably (items lost in post refunded without question), wrong spokes/nipples sent so many times I lost count, all without cost to me.
Quite a few items I received were of questionable quality eg (to name a few) ..... a new ski slope with incredibly badly tacked on (and rusty) nut for the air filter, a new alloy mag gear that needed its teeth filing to fit, b31 axle nuts of wrong diameter to fit the frame slots, fork seal holders that the chrome falls offs etc etc
This was all "forgivable" as I've had duff parts from other bsa parts suppliers before, and I know that most of the parts DF stock come from the same manufacturer (eg Aerco) that similar companies to DF source from.
But then DF cost me a few hundred extra dollars by not following simple shipping instructions (for rims) and even though I never mentioned compensation DF would not acknowledge any fault at all, or that they were obliged to follow any such instructions, and frankly, they were rude about it.
From what I can see the children of the long time owner of the business have taken over the running of DF in the last couple of years, this may explain the decline in service?
Either way, I buy from elsewhere now, whenever I can.