I have an appointment on Jan 29 for H1B stamping at Matamoros. I cannot make it on that day and was trying to reschedule. I had one rescheduling opportunities left and from this Monday (Jan 22), the system is showing me that my appointment is confirmed and rescheduling opportunities left as zero. I contacted help desk and they told to call US Embassy in Mexico’s Customer Service Center which is a paid call. Anyways I have decided not to goto Mexico at all for stamping. Do I need to call embassy and cancel my appointment or just not showing up for interview is fine? Thanks in advance.