An A320's navigation system would not autotune nor allow the crew using STBY NAV to manually tune a runway's ILS frequency. The crew assisted a Contract Mechanic following Maintenance Control's directions to correct the problem.

Narrative

On our initial decent I noticed that the autotuning of ILS 8R; our assigned runway; was not autotuned; as our RadNav page was indicating blank. Tried selecting different runway; was no help. Went to STBY NAV and tried to tune in manually; that also did not work. Called Maintenance and under their direction cycled several CBs. We eventually got our STBY NAV to work as well as our auto-tuning. Weather was IFR; with low clouds and visibililty. Contract Maintenance came out (1 Mechanic). This Mechanic although a very nice individual; in my opinion was not qualified be any means to work on a Commercial 121 A-320. My First Officer and I had to stay in the cockpit to assist this Mechanic in complying Maintenance Control's instructions. We eventually had all RadNav back to normal working order. My point here is that safety is being compromised by this Air Carrier not having qualified contract maintenance at these stations. We never found out what caused this malfunction. The resolution to this issue would have been uncertain if my First Officer and I were not there to assist. This Air Carrier is getting away with not paying for a qualified mechanic; and most certainly not paying us (the more that 2 hours that it took) to assist this Mechanic; and is probably counting (relying) on unpaid Flight Crews to assist the unqualified contract maintenance. This Carrier needs to hire/ensure that we have qualified contract maintenance at these stations and compensate the pilots if they expect; or would like for us to stay and assist maintenance.