I use Tesco coffee beans, a Bodum grinder and a Bosh filter machine.
It always tastes bitter though, sometimes completely undrinkably so.
What's a bosh filter machine - is that one of those drip thingies where you put coffee into a basket and hot water drips through the grounds?
If so, I'd suggest binning it entirely. You'll get much better results from a plunge pot (cafetiere).
Bitter coffee means over- or under-extraction. Under extracted coffee is watery, bitter; over extracted coffee is sharply bitter/acrid. Either way, the grounds are not spending the right time in water at the right temperature.
For all coffee, the key is ensuring an even ground size - if its mixed, then the big grains will under extract and the small ones over extract resulting in mostly bitter coffee.
Next is the water - too hot=overextraction, too cool=underextraction so it must be at 92C - under boiling point
I'd say this is very difficult to do with a blade grinder and a drip filter. With a cafetiere, grind size must be quite large (but still even) and when its ready, pour it off. Get a burr grinder, even a hand operated one!!
If you're using a blade grinder, you could try grinding for short bursts and shaking the contents for better distribution.