Sorry to hear you're having problems. I've been using a Digiflash routinely for the last 11 months with excellent results. It tracks my Gossen Luna Pro F "perfectly" within the 1/3 stop limits of the Digiflash readout.
I do have one word of warning. The meter seems to take a reading over a very short time frame (called a "gate time" in electronics), likely shorter than the typical 50-60 Hz AC cycle, which leads to odd readings under flourescent or similar lights. See my article on APUG. To get an idea if it's doing this, hold the metering button down and watch the +/- relative exposure indicator. If it cycles quickly up to a stop or two, you might be in a situation where gate time is shorter than the cycling time for an electronically cycled AC light source.