If you are looking to upgrade or downgrade your plan, you cannot change to a different plan that is on a promotional pricing. Instead, you can only plan change onto the standard pricing for a plan.
Importantly, plan changes can only take effect at the start of your next billing cycle. For most customers, this will be on the 1st of the following month.
Please let us know what plan you would like to upgrade or downgrade to and we'll schedule the change for you if possible. After that, it's just a matter of waiting for your next billing cycle for the change to take effect.