If the non-start condition means you get no sound at all, then the problem is NOT the ignition. Perhaps they mean the ignition switch?
It could be the battery, or the battery connections or cables, or a relay, or the ignition switch.
I’d get a voltmeter and next time it doesn’t start, check a few points, such as battery voltage and starter voltage (at the solenoid and at the main starter terminal).
Also try wiggling the ignition switch next time I doesn’t start.