Upgrading from Bronze to Silver, will I receive a pro-rated refund for the rest of Bronze?

If we buy a year of bronze and then in 2 or 3 months realize we need upgrade to silver, how does that work? Do i get a prorated refund for bronze or do i have to pay both for both of them for a year?

If you create a subscription and change it to a different subscription, you will received a pro-rated charge or refund for the remaining time on your currently subscription. 

If you buy a year of Bronze and find you need Silver at some point, you will receive a credit for the value of your remaining time towards your Silver subscription.