Sometimes the lax neck skin cannot be totally tightened even with an excellent Neck Lift and Platysmaplasty. In these cases a revision is necessary or if the skin pulling is small then laser resurfacing can be done.
It is very difficult to precisely confirm a diagnosis without examination and investigations and the answer is based on the medical information provided. For exact diagnosis, you are requested to consult your doctor. I sincerely hope that helps. Take care and please do keep me posted on how you are doing.