"Server is Full" problem - Why is this happening continuously?

I have already inquired and addressed this situation to Customer Service and I am currently waiting for their reply.

The "Server is Full" problem has occurred on me for three times this month already. Does anyone also have the same problem as me? Does anyone know the reason why this continuously occurs?

I am just curious, why does this happen often?

I was excited to accomplish my daily missions for CF Pass and Mutant Honor Missions but it seems that I can't and will probably have to wait a day to wait for a response on the matter. What a waste for today. So Disappointing. Sigh.