What happens if your reference is poorly organised?

Although I'm just going along the lines of completely hypothetical scenarios that involve pessimistic thinking here...

What happens if:

a) your reference is poorly written (i.e., it contains a ton of grammatical mistakes)?
Can you ask your referee to make small grammatical changes, so that the universities don't automatically put you in the 'no pile' the moment they see your application?

b) you have no reference submitted whatsoever
Your referee vanishes for a week and your reference doesn't get submitted and you basically don't get a reference of any kind. Does that mean your application doesn't go ahead and you instantly have 5 rejections or will universities see that you have no reference, but still see the rest of your application (like personal statement, etc.)?

Stressed.

For scenario a ) you don't normally see your reference anyway*. And the universities are judging your overall application not wether or not your referee can string a sentence together.

And for scenario b ) apply in (very) good time.

*unless your referee optionally chooses to share it with you, or you pay UCAS £10 to get it after it has been submitted.

Thanks for your reply.

With reference to b) firstly:
But let's say you've done absolutely everything there is to do for UCAS. Like your PS is ready to go, you've selected your courses and you've done all of the UCAS bit by September, etc. (well in advance of the deadline). If you don't get a reference for whatever reason, is that the end of your application? It's really the only part of the application that you can't really do much about and if I have to annoy my referee to death to avoid hassle, I think I will tbh.

And as for a):

Will your referee know that you paid £10 after making a request to see the reference they wrote?