Excuse me? Can anyone out there help me out with a concern I have with Skyrim please?

A few days ago I picked up the game again to continue with the quests as I hadn't played in a good while.
I just gained a level up (character level from 43 to 44) and I want to gain an extra skill training in Lockpicking.
My current lockpick skill is 96, (as I said in my title) and I want another couple of training skills with this.

But my problem is, that Vex of the thieve's guild in Riften (she is normally the only one who trains you in lockpicking) no longer
appears to have a dialogue option for me, where she would normally open a box with the lockpicking info and I choose that skill to level
up e.t.c.

I know there are some bugs in this game, (quests impossible to complete due to the structure e.t.c) particularly on the X Box 360, (which is what I've been playing this game on since I first bought it) but I really don't understand it.

All skills in this game finish at 100.... not 96 or whatever! Am I to be forever stuck at 96 here with this skill or what!?
Is this where all other skills finish at too? (i.e. 96) Lockpicking is my highest skill in this game right now.
So I'm still able to gain experience with other skills which are nowhere near 90 yet either.

So what about this problem I'm having?
Why am I stuck at 96 with Lockpicking?

Can I still get this experience from the Khajit caravan guys? I always find them so diffcult to find, which makes the thieves guild a lot quicker and easier.

OR

is this yet another annoying bug in the game!?
If so.... anyone else out there with the same bug here too?

You can't get training once your skills are at 90, or something like that. You gotta level it up manually.

...And the last few levels can be a PITA since the levelling is so slow by then. I've never had lockpicking so high, so I can't give you any further advice, except that the higher level locks you pick, the faster you should be levelling up.

After level 95, you can't train the skill. (most of them anyways)
So Vex's behaviour is normal.

Lockpick is very easy to level to 100.
Just go into a town, wait until nighttime, then sneak around a pick all the locked doors in town. Since most of them will be Adept or Expert you will get a good chunk of experience.
Then move on to the next town and repeat.... It won't take too long to be 100