Termination procedures
Termination has to be done following due procedures.
Employee productivity review
The system of reviewing the productivity of each employee should be public knowledge for employees being assessed. This includes targets, quality, the number of products rejected by QC, etc. Employers should not suddenly, out of the blue, state poor productivity and then terminate employees.
Principles of natural justice
From the bare details given by you, apparently, the termination is not in accordance with the principles of natural justice. It is advisable to take up the matter with higher management in a factual manner in writing, preferably by Speed Post for acknowledgment purposes. Additionally, seeking advice from a lawyer who specializes in HR matters is recommended.