Changing Creative Cloud Plans

If I have 4 months left for my current annual plan and I wish to change to a different annual plan, would the renewal date be changed or I would still have 4 months left until the renewal date?

Plus: I've tried to contact Adobe New Zealand using the contact number 0800 485 948  but it doens't work: "The number you've called is not available from your location." Why is that and is there any alternative phone number?

Thanks,

Kent