What does the two "have had it"s mean respectively in this context?

Question

‘You heard me—OUT!’ Uncle Vernon bellowed, and even Aunt Petunia and Dudley jumped. ‘OUT! OUT! I should've done this years ago! Owls treating the place like a rest home, puddings exploding, half the lounge destroyed, Dudley's tail, Marge bobbing around on the ceiling and that flying Ford Anglia—OUT! OUT! You've had it! You're history! You're not staying here if some loony's after you, you're not endangering my wife and son, you're not bringing trouble down on us, if you're going the same way as your useless parents, I've had it! OUT!’

_{Harry Potter and the Order of the Phoenix}

It seems to me that the two "X've had it"s mean differently in this context. I looked up the phrase "have had it". It has many meanings. I'm not quite sure which ones fit for the context. My best try would be: the first one means you have had enough of those stuff like puddings exploding and etc. and the second one probably means I couldn't tolerate any more. But I'm unsure if my understanding is correct?

Answer 1

In this context, the expression you've had it means you're in trouble. You've used up your chances (to do whatever); now those chances have expired and you will have to take the consequences (whatever those might be).

The expression is widely used to indicate that someone is in trouble as a result of their actions/behaviour or some other misfortune.

The police are after you and now you've had it.
Your project has run out of cash and now you've had it.
You've been caught double-dating and now you've had it.

The expression can be used in other contexts to mean that someone has had possession of some object.

I've been looking for my hammer and as I recall, you've had it

although the construction is more likely to be you had it (last)

I've had it, on the other hand, means that I have endured as much as I can take. I've been worn down. I can take no more. I'm through with you. My patience is exhausted.

This expression is usually followed by the likely consequences. In the example you quote, Uncle Vernon is telling Harry that because his actions have distressed the family, he will have to leave the house.

Answer 2

The first use, where Uncle Vernon says "You've had it!" corresponds to this meaning on the page you linked to:

If you say that someone has had it, you mean they are in very serious trouble or have no hope of succeeding.

Uncle Vernon is saying that Harry is in deep trouble because of owls, puddings exploding, etc.

The second use where Uncle Vernon says "I've had it" uses this meaning (again, on your linked page):

If you say that you have had it with someone or something, you mean that you are very angry with them and do not want to have anything more to do with them.

(also have had it up to here (with somebody/something)) be unable to accept a situation any longer: