I say sending old fashioned letter will draw attention as the postman will complain about increased work load but seriously I say it's better than email which can be deleted in a sec.
I also think people should be reasonable, make sense, use numbers, statistics. People who make decisions do not care about feelings. Do not tell them a sad story, hand them solid facts. Bombard with true research.
Money wise they have decided to sacrifice some as that's how the group of people doing poorly on levo only are seen. People that can be and will be sacrificed for greater good. This group is seen as statistics and statistically if 90% do well then boohoo the 10% they pay the price. 10% is considered as acceptable number to sacrifice.
Poke the structures. Show them it's about patients rights to receive treatment that restores the best health in given circumstances. Explain how unacceptable it is that one treatment only applies as it means the rest of you not just only feel unwell but end up suffering from multiple health issues that in most cases would avoidable. Explain it would take the burden off of not just the doctors but health care system if everyone would receive proper treatment.
We have offered them sad stories, time to play their game and bombard with cold facts. They do not care if you have lost your job and family, shit happens. But they care if you tell how much you cost to health care system. For them you are a number.
That's what I am going to do over here in finland!