I saw on this page: http://www.japanesepod101.com/helpcenter/billingsubscription/pricing#7
All subscriptions will renew at their normal subscription rate. If you have signed up with a coupon code your subscription will renew at the normal rate unless otherwise specified. If you would like to extend your subscription at a discounted rate during a promotional period you may do so by cancelling the renewal of your current subscription and then purchasing the new, discounted subscription. The new subscription will begin when your current subscription ends
So I duly canceled my existing subscription and purchased the new, discounted one. But now my account shows I have one ending in July and another starting tomorrow and ending in May 2018. But the FAQ said it would start when my existing one ended so it should have slid across to July 2018.
Can this be fixed? If not, don't worry about it, I'm not looking for a refund or anything as it's well worth what I've paid, but maybe the FAQ page should be corrected?
edit: All sorted now, thanks for your help!