Autoradio High performance RDS indicator static

I have been driving an xc60 with high performance autoradio since 01/2011. My son has noticed that the title display does not run through and usually half-cut titles are displayed. On demand, I received the answer from the volvo dealer that the reference line should not go through on some “legal regulations” (not defined in more detail). I then asked the boss, who had probably never noticed this at the volvos before and wanted to inquire as well. But I did not get a satisfactory answer. If my son had not drawn my attention to this, I would probably never have noticed that, since then I have been annoyed every day.