Cellular data and roaming set to off, but roaming data still occur and charged by operator

Sweden calling: I first notised these data charges on my bill 2+ years ago. I had a very long exchange with my cellulär provider's customer service over many weeks. Eventually they talked with someone in their technical department who said that this is an issue with iPhones. I then surveyed other expatriates in a Swedish Facebook group and found that both iPhone and Samsung suffer from this. In some cases the Swedish carrier credited the user for the data, in others (mine for example), my carrier makes me pay it. Data usage on my latest bill amounted to about $15 even though cellulär data was turned off the entire time. Each day the usage is minimal, well below what anyone would likely log if they truly were using cellulär data. See below from my most recent bill showing date/MB/country/charge in Swedish kronor. To say the least this is (a) irritating and (b) a great opportunity for a class action suit against Apple. I'm amazed the problem still exists (if it does with the newer phones, that is. I'm using an SE purchased 8/2016 running iOs 12.2)

Apple Technical Support, where are you in this discussion???

I utlandet, Surf

190404 0,2387 USA 5,86

190405 0,3839 USA 7,81

190406 0,3493 USA 7,81

190407 0,2585 USA 5,86

190408 0,3110 USA 8,79

190409 0,3675 USA 7,81

190410 0,3359 USA 8,79

190411 0,3633 USA 8,79

190412 0,4810 USA 9,77

190413 0,3760 USA 12,69

190414 0,4169 USA 10,74

190415 0,3699 USA 7,81

190416 0,4971 USA 10,74

190417 0,3276 USA 9,76

190418 0,2107 USA 8,78

190430 0,3696 USA 9,77

There's nothing that any of us users in this user-to-user forum can do about it. You will have to take it up with the carrier.