Game time card with entry subscription

Ok forgive how noobish this is going to be. I've only gotten into this game a few months ago and have been paying for an entry subscription (one character per server) via my debit card. After finding out about the promotion through Amazon for free in game items after spending $20 or more on qualifying items I decided to buy a time card since that seemed to make the most sense. Now when I go to add it it's telling me I need the standard subscription ($2 more/mo for up to 8 characters per server). This can't be the only way to use a game time card right? I have no need for extra characters and feel like this game is designed to eliminate the need for alts completely. Is there any way to get around this? I've barely got time to be catching my one character up there's no way I'd ever want to make more. Do most of you on here have multiple characters? Do you just pay by CC so you don't have to deal with all of this?

Edit: I just had Amazon refund me. I'm not participating in Square's BS trying to force people into paying more for things they won't use.