Multiple electronics issues after having new reconditioned handbrake motor and handbrake switch installed

Wondering if you can help me. Since mechanic put a new reconditioned handbrake motor in, also he said handbrake switch, and brake switch needed replacing in. So new ones purchased. Oh and new battery. He hasn't been able to re calibrate them. :( Also I have no horn, radio won't play, no windscreen wipers, windows won't operate, indicators. :( Is this an easy fix? Is a wire loose? He's peeing me off, I'm due to go away in a weeks time. Recently split with my ex, so I know nothing about cars, apart from changing a wheel, and checking water/oil/ etc. Any help would be much appreciated. Thanks. Lou xx