Help! Miltonia with drooping leaves and yellow brown leaf.

[vg5138]

Firstly, hello (first post) and thank you for this informative website.

290117 I bought a Miltonia for my mother's 90th birthday from M+S. It arrived in bud on two stems and all the green leaves were upright. Within 4 days 2 leaves started to droop, now about 4 or 5 drooping. The buds opened (and still are opening) and the flowers are very nice. But after a further 7 days or so one small leaf suddenly went yellow overnight and now is half brown.

It looks like it is dying to me.

The potting mixture looks fairly dense (moss like) with a thin layer of fine bark on top. It looks too dense to me when compared to our Dendrobium which is situated on the same table in a west facing window and is potted in a chunky bark pieces and nothing else. The Dendrobium is thriving (and has been for a few years).

When I got the Miltonia , I watered it lightly with tap water (a la Dendrobium style) after a week I watered with a bit more incase it was too dry. However I have no experience with Miltonia and do not know if it should be treated the same as our Dendrobium. If it should, I would be inclined to repot it in a bark mixture like the Dendrobium.

The temperature range is 17 - 24 degrees Celsius in a centrally heated house, warm air heating.
Any help would be appreciated, as it was not a cheap plant and was a special present for my mother.

Thank you.
(I believe I cannot post photos until I have 5 posts).