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I don't recommend to in-app upgrades as they are higher priced then the Upgrades via Spotify.com.
I think the best way to check what's going wrong, is to get in touch with the Spotify team.
You may get in touch with Spotify via their Twitter page (@SpotifyCares), or by following this link to send an e-mail.
If you send an e-mail, please check your inbox (and spam box) to check for their automatic reply. Once you get it, please reply to it immediatly (even if it's from an no-reply e-mail addres) to make sure an Spotify employee will get back to you as soon as possible.