Look at my poorly orchid please ?

I would let them know, but in the meantime you could chop out the sad yellowing bits, remove from the pot and rinse off the roots. If you've got orchid potting mix, repot (after washing the pot thoroughly). One stalk looks ok.

When you water it in future, stand the inner pot in water for half an hour, allow to drain well before putting back in the outer pot.
Perhaps it was overwatered before you got it.

If it dies, you tried!!

My sister had an orchid similar to yours FC.
She had managed to keep it in flower for quite a few years .
It was tucked in the corner quite close to the kettle.

The orchid was not in direct Sun light and was on!y 'watered ' by the steam from the kettle.

FWIW I got some orchids in August and the accompanying instruction was to hold them under cold running water for 20 seconds once a week - which I did, and they're thriving. Rotate them so they each get a chance of plenty of daylight (north facing windowsill). Not like me, I'm a world expert at killing plants!

Can I just ask, are you sure it begins with D? It looks like a cymbidium to me.

How long have the flowers been blooming? Perhaps it's just dying back naturally? As long as the leaves and roots are healthy, it's probably nothing to worry about.

SpringyChicken it’s still partly in bud! I chose it specifically because it wasn’t in full bloom.
The buds and flowers have now all gone black and dropped off. All in a matter of 4 or 5 days.
I will let you know what the garden centre say when I hear from them