I can't see my Seagate hard drive Dropbox Backup offer in my account nor an option to cancel it

I've recently purchased a Seagate Hard Drive and it came with a Backup plan offer from Dropbox. I have activated it and I'm backing it up as we speak, although when I go on my subscriptions page, it doesn't show me any information about this offer, it just says I have Dropbox Basic and that I'll be charged 8 Dollars a month. I can't even cancel the subscription after 6 months free offer ends. Any advice on how I can resolve this painlessly? I don't want to cancel the offer, although I don't appreciate not having the option to.