Possible electrical fault

Morning all, new here and just looking for a bit of advice regarding a few electrical faults with my '05 Fabia 1.2 that seem to be all connected.

Had this car just under a month now, purchased third hand (2 previous lady owners, 80000 miles on the clock) and was seemingly running fine, except my dad had noted the ventilation system had been "a little temperamental" while he was getting checked over at the garage but they said they couldn't find a problem.

As we've hit autumn and the rain and cold has come I started my car and the rear windscreen wiper and ventilation system wasn't working. I turned the engine off and back on - nothing. Checked all the fuses involved and they were normal - after leaving it for a bit  turned it back on and everything was working again fine. Was fine for about 2 weeks until I got home from work on Friday and the ventilation system had cut out on the journey home - again the rear windscreen wiper didn't work. It hasn't worked since, fuses all in tact, then yesterday in the evening my front electric windows stopped working half way through my journey (open) had to turn off engine and back on again to get them to wind back up.

As it's old I was wondering if there could be a bit of moisture causing resistance to play up in the wires and wonder if anyone has the wiring diagrams and is able to tell if any of these are connected via a loom or something (not very technical when it comes to cars )

Is it fixable? DIY or special job? and rough costs if anyone knows?

Thanks so much for your help!