Bike polo mechanics & fixing

Does anyone find that they need to re-adjust their BB7 disc caliper on an almost game by game basis? I've rebuilt it, put another one from the spares box on, tried taping the adjuster barrels on the caliper, taken any slack out of the cable, using ferrules and a speed dial lever, and nothing stops the caliper loosening. Sometimes to the point where I have no brake and I crash. I'm front disc brake only, with guards, and frustrated/bruised!

If it's not simple, then I'm going hydraulic.

yeah, mine got knackered pretty quick and kept loosening.

so i went hydro. we'll see how long til something catastrophic happens