It is odd to receive botox, instead of filler, by accident. However, I often use botox in the lower lip (where the pink of the lip meets the skin) to soften the wrinkles that occur with pursing of the lips. I use filler to enhance the lower lip. We can also combine these treatments.
This is an unusual occurrance, but 3 units will not create any lasting problems. But you will have to wait until the Botox wears off. Fortunately, the effects of Botox are temporary.