The problem with changing the tariff plan. please change my tariff plan/
What’s ‘tariff plan’? Are you meaning PPT (Pay Per Traffic) data plan on Mudfish? Please check Data Plans section.
data plan can be
changed only once a month, I need you to change it to subscribe now, I
made a mistake and chose not what I wanted
When I checked your account it seems your account is already Subscription data plan. 
Please check it again.