Hi Macca - I'm surprised you haven't had more replies to this as it's a big issue with hrt. I'm severely prog intolerant, even to my own prog. I've tried them all including stopping hrt entirely. They all get me in the end. Now, realising I can't function completely hrt free, well, not right now, and at the point of being referred to gynae for hysterectomy, I seem to have found a workable form of hrt in a half fem7 sequi patch. It's low dose, so might not suit you but this amount of prog is ok for me and it's continuous. I really believe if you're truly prog intolerant, the highs and plummets of a cycle aren't a good idea, rather, find the lowest dose possible and take it conti.
Don't know what you've tried or how much, let us know and you might get a few more suggestions. One thing you might consider, and I am, is a Jaydess coil. It's not licensed for hrt in uk but some gynaes are willing to fit it and you can have it fitted for contraceptive purposes if you're in that zone. It's significantly less prog that Mirena and acts ‘mostly' locally so the systemic effects are reduced.
Post more about your experiences.