Make a small timeline
The allowance reset, statement date, payment date and minimum-term end are not necessarily the same day. A partial first period or a mid-cycle change can explain why an early statement differs from the expected pattern.
Understand automatic settings
Automatic payment, top-up and allowance renewal may be separate controls. Find out what each one funds and what happens if it is disabled. A stored card does not establish that the intended bundle is active.
Keep the confirmation
Before changing a plan, ask whether it starts another commitment, removes a feature or takes effect at the next reset. Save the response and check the following statement. Where a minimum term finishes, confirm what continues rather than assuming the line closes automatically.