Have you ever heard of Sculptra injections under scalp where facelift is performed to reduce labial folds?

When you say "labial" folds, I assume you mean nasolabial folds.  In general, I feel these are often improved by injecting Sculptra into the cheek area, above and to the side of the folds.  It is true that Sculptra can provide some lifting by adding volume, but normally, the farther distance you go to inject from the site you are trying to lift, the less effect there is.  It is difficult to give you advice about your particular treatment without seeing photographs of you or examining you.  I would discuss your concerns with the physician who treated you.  

I don't think that the NLF's will benefit from injections in these areas. I know some people are injecting the scalp for lifting but I don't think there is much benefit in doing this.The preauricular area is often injected to pull things back and I agree with that but not the retroauricular area.