Tree is right, Kittypal. The sentences
(1) Shelly had enough, and
(2) Shelly had had enough
are different. (1) is simple past tense, while (2) is the so-called past perfect.
I'll bet these constructions won't sound strange to you at all in the present perfect:
(3) I have had it with your stupid complaints!
(4) Tom is saying he has had it with these stupid complaints.
Now put both of the above in the context of a past tense verb, and see what happens:
(5) I told you then I had had it with your stupid complaints, so why did they continue?
(6) Tom said that he had had it with these stupid complaints.
Tom probably also figured that, like him, Shelly had had enough of the stupid complaints, too.

I'll also bet you would have no trouble with these tenses if the main verb were not
have itself. (1) and (2) are perfectly parallel with
(5) Tom has seen it all before.
(6) Tom had seen it all long before then.
[This message was edited by maiku on 12-13-03 at 03:32 PM.]