You'll need to explain your issue/question more clearly if you want assistance from the Community Forum.
What exactly do you mean by "upgrade the plan/change the plan"?
What plan have you been buying up to now and what one are you looking to buy going forward?
If you want to choose a different plan then you just do that yourself at checkout time when buying your plan:
If you need to contact 48 support about this then see the links in my signature below.
