A personal appearance interview is required as a standard part of this process. This can increase the processing time. It is expected fewer waivers will be granted for the interview portion of the process.
NACS cannot assist you with the interview process, nor can anyone representing NACS call the embassy or consulate on your behalf to provide support for granting a visa. If you are denied a visitor visa, you may re-apply if there is new evidence to overcome the basis for the refusal. In the absence of new evidence, consular officers are not required to re-examine such cases.