My washing m/c, which is connected for drainage at the kitchen sink has just *almost* flooded the kitchen by means of overfilling the sink when draining. Now I'm no expert, but that tells me there's a blockage between the sink and the main drain.
I've tried a traditional plunger on the kitchen sink, and a syringe type plunger but both merely blow crap out of the overflow (straight down my shirt, lovely). I can't think of a way to block the overflow to increase the pressure so I'm looking for alternatives.
I've come across the Mr Muscle range of two products, details here: