Yes I know that Illia is bugged and has some serious issues, and i have encountered them, she won't give me any dilogue other than the generic, 'need somtings', or' yes?'. Any suggestions anyone?

You're screwed if you dismiss her.

Unless you are on PC.

Indeed this is why I just tend to make her a steward or use my PC Skyrim to add her to the follower faction again lol

Why what happens if you dismiss her out of interest?

You can't recruit her again. Just generic dialogue. So if you dismiss her while she has your stuff, the only way to get it back it to either kill her or pickpocket her.

Dialogue that allows an NPC to follow the player is dependent on relationship rank status.

Relationship rank data is not saved for actors templated on leveled lists. Illia is such an actor.

However, she's not a good choice for a follower -- aside from the above, quirks about her inheriting her spells from a list of warlock bosses means that she can be left with some underwhelming spells if she's encountered at a low level.