I couldn't agree more @eriluks on buying your phones online and just inserting a SIM card from the carrier. It's such a better value to not be under any agreement and simply own your own device. Especially considering the customer service often provided at carrier locations can be extremely lacking.

I'd recommend converting your SBD to BTC and use Purse.io to buy a new device from Amazon. You can usually get 20-30% off products by spending BTC there. https://purse.io/?_r=D_X7Rr