Use this PUT method to update the type of billing plan to assign to
the Constant Contact client account. The type of billing plan determines
which Constant Contact product features that the client account can
access. The billing plan type (plan_type) that you enter must already
exist in the plan group. Attempting to change to a plan that is currently
not available within your partner plan group results in a 400 error
response code.
When you create a new client account, the plan_type defaults to TRIAL
and the billing_day_of_month defaults to null. The billing_day_of_month
property is required if a client account is not set up to use single
billing. You can change the day of month (billing_day_of_month) in
which to bill a client account only when changing the plan_type value
from TRIAL to a different plan_type, otherwise the billing_day_of_month
value you enter is ignored. You can choose to enter a specific day of
the month or accept the default value, which is the day on which the
plan_type value changes from a TRIAL plan to a different plan_type.
Changing the plan_type from TRIAL to another plan_type automatically
changes the billing_status from Trial to Open.
Only technology partners can access partner endpoints and partner endpoints
cannot be tested using the API reference tester.
For more use case information, see PUT Billing Plan Details for a Client
Account
in the API guide.