you can make a CS generator for fairly cheap. sounds like you are in the UK? i bought an inexpensive one for $40 from here but i have no idea if they ship to the UK.
you then attach these to three nine volt batteries, find a way to stabilize it, and put the two silver wires in some distilled water and it will generate CS.
i don't use CS at all anymore for several reasons, including the concern that it kills off internal flora. but using it externally i think it fine, and besides you are dealing with something pretty severe, so severe measure may need to be taken.
i would DEFINITELY start with external application of hydrogen peroxide on a regular basis if nothing else. get some food grade for better results.