please advise

[Jolyn78]

How come they do not know to get the watch for me?

Is there anything wrong with the sentence?

[Jamie (K)]

The sentence is grammatically correct.

[Beeesneees]

Hi Jolyn,

'How come...' is a very informal way of saying, 'How is it...'. In all but the most informal of settings I would use one of these:
How is it that they do not know they should get the watch for me?
or far more simply:
Why don't they know they should get the watch for me?
_________________
Cheers m' dears!

[Jamie (K)]

"How come" added in front of the ordinary word order of a sentence is asking "why".

"How come" is fine in most daily usage, except when the situation is extremely formal, but we generally do not write it.

[E2e4]

How's happened they do not know to get the watch for me?

Possible?

[Beeesneees]

No.
_________________
Cheers m' dears!