The frequency that X-Plane uses is 109.70 in X-Plane and that works fine.
The frequency MAY be 109.75 in the real world (it is according to my charts) - but X-Plane uses 109.70.
If you see 109.75 on the map, file a bug with Laminar Research, because there may be the old "curated nav data" dilemma at work here.
X-Plane will NOT use any updated data source like Navigraph or Aerosoft for the ILS approach information. The only way to change those is to file a bug report on the Scenery Gateway site, so Robin Peel can change the data manually. The reason is that they don´t want ILS approaches that don´t line up perfectly (because maybe the airport isn´t in the right spot).
Further reading: https://developer.x-plane.com/?article=navdata-in-x-plane-11
Jan