Hi guys,
I recently (just a couple of weeks ago) had exactly the same problem. The original factory fitted Visteon radio tuning function just gave up, meaning it could not lock on to any station, neither FM or AM. Took it out, measured the lead to the antenna and that's fine. Plugged in a piece of cable into the aerial lead of the radio and still nothing. Took it to an electrician who fixes among other stuff Stilo radios as well and just as I presumed the tuner of the radio broke, so I was left with a choice to pay either 40 euros to change just the tuner or get a complete used but good radio with a CD player for 60 eur. I went with the latter option. Mind I say that the original radio was still a cassette player one
at least now I have a CD player Visteon radio all working fine, it was just a swap, out with the old, in with the new and presto.