@ScottMacFarlane
If you chose "renew plan now" then you've immediately discarded your old/existing plan and immediately begun your new/chosen plan. You got charged the full price of the new plan, you didn't get any carryover or refund or credit or pro-rated returns from any unused days or talk minutes or data remaining on your old plan - it's just gone.
If you chose "renew plan on next cycle" then your old plan ends when it's supposed to end and your new plan begins immediately afterwards.
If you lost funds by making the common mistake (basically paid for a plan, then deleted it and paid for another plan right away) then you'll have to ask @CS_Agent to correct your account balance. Don't feel bad, the fault is really caused more by uninformative and uncooperative Self-Serve interface than by customer decision.
Taxes are unavoidable and assessed at point of payment. A Payment Voucher costs price+tax. AutoPay charges your credit card price+tax. But once the funds have been paid/deposited to account balance they are not taxed again. A $50 account balance will pay for a $50 plan.
