For complaints received about you, an investigation is due to be set. That  so, the AFI will file a formal investigation. After is done, you could end with a no action notification or a warning letter Notice of Investigation placed in your file.
Is the investigation been initiated by Vehicle Safety?
No, is not.
I was told i could accept the charges so no hearing would be held, but what if i reject the offer instead?
If you take that action, then inevitably a hearing will take place.
So, the best action course would be to accept those charges, isn't? That would help me?
Yes, it would. In that way, no hearing would be held or even required.
I guess that would do for the better. What will happen after i receive my penalty?