Help with identifying tree and infestation

I have this tree/shrub (it's about 4ft high) that is 2-3 years old. I have no idea what it is, but it's deciduous, has dark purple leaves and a woody stem. It is now covered in little white flecks which you can just about make out in the pictures, some black flecks that are larger and some small and fairly ordinary looking caterpillars (which I've picked off).

I don't really want to cover it in anything toxic, but equally it's a very pretty plant that I'd like to keep. Any ideas as to what it, or the infestation, could be would be grand. And any hints or tips of what to do next would be even better. Thanks