How to unhinge Apple ID from Tinder?

Dear Community,

there was no iPhone App Store Community, so I posted it here.

Please move to a more suitable place if necessary.

Here's my problem:

I've installed the Tinder app two years ago and created a facebook account for it (because I don't like facebook for privacy reasons).

When I found a girlfriend, I uninstalled Tinder and deleted the facebook account.

Now a year and a half later it all went down the drain, I want to start looking again, and I've already created a new facebook account for Tinder. I can use the free part of the app, but when I try to buy Tinder Plus, somehow this daft App Store remembers that there was once a subscription with my Apple ID - which is a totally different email than both my old and new Tinder-facebook account!

How can I delete the connection between the Apple ID and my obsolete facebook account so I can start using a new account with the app?

I've already tried to create a facebook account with the email I'd used then, but the App Store still spits out the same message when buying Tinder Plus: "Error with purchase, item already in use." [loosely translated from German]

It offers to "restore purchase", but then gives out "Not possible, Code 7, please contact support"

Every help is very much appreciated!

Voushcoon