What model is the Samsung as i have had the Astra UHD 4K test channel on 28.2° east working on both a 55" 7500 model and an 8500 model both from 2015 with the built in satellite tuners.
A satellite tuner does not have to be so called 4K compatible and i am flabbergasted that a samsung UK Tech person would tell you this, The tuner just picks up the signal its up to the TV to do the rest.
What you will find is on a UK TV set is the satellite side is preset for freesat and you have to put this into manual mode and store the frequency required for the channels you want