Creature with spell like abilities that later gains spell casting ability. How does this interact?

[TheDisjointed]

In short, a creature with spell like abilities gets wizard levels. Does the CL of the Spell likes stack with the wizard level or no?

[GM Rednal]

Generally, a creature's Spell-Like Abilities are fixed and do not change (unless they grow as described in the creature's description). If they do grow, they tend to be based only on Racial Hit Dice, not Class Hit Dice.

If a normal creature with SLA's gets levels in Wizard, their SLA's will not change in any way.

[Azothath]

Spell-like Abilities(SLAs) and spell casting are separate abilities and don't interact.

SLAs don't grant knowledge of a spell, qualify for early entrance into a class via spellcasting, and can't be counterspelled in general. Usually SLAs run off of character level or Hit Dice.
SLAs are an easy way to give some creatures limited standard spell abilities without having them go through Spellcraft and the spellcasting system.

[TheDisjointed]

Thanks guys