@felicity_law
I take it you were suspended. It can be tricky changing plans to lower priced one when your voucher amount covers the plan amount of a more expensive plan. The key is to change plans/subscription first before entering the voucher pin code. Select the plan you want then choose "Change immediately" and you will be redirected to the payment page where you can enter the voucher pin #.
If no option is presented other than a card payment you can still load your voucher using 611 on your phone and the system will automatically take the new plan payment from the voucher payment as it gets loaded onto your account balance.
Contact customer support and explain you didn't know how to change plans when reactivating without the system taking your old plan amount first from your voucher payment. They will credit your account the difference and ensure you have the plan you intended to reactivate on. Lots of customers including myself have made a similar mistake.
