This kind of problem is way above my pay band but I can understand why a Hyundai dealer would deny responsibility for this phenomenon. Having said that, I shall presume, unless corrected, that the problem only manifests itself on DAB reception and not on FM. Should that be the case, then the remedy seems pretty simple. I use a mix of FM and DAB station and apart from the additional information produced in DAB stations, there is no audible difference in quality of sound that I can discern.
The input from ‘PhilHornby’ is informative.