Showing offers to paying members

I launched a site a few weeks ago, and ran a launch discount on both monthly and annual tiers.
A monthly subscriber has asked if they could upgrade to annual before our discounts expire.
But when they click on the annual discount links nothing happens - they don’t see the option to claim the discount. All they can do is click on the “change subscription” but they see full price there.
I realize this is because they are a paying member, so my question is:
How can I display an upgrade offer to a paying member?
I would love from them to pay an annual subscription, but cannot figure out how to do it. I would also like to extend this idea by offering upgrades to paying customers for higher levels - they would pay an upgrade fee for the higher level.

This is what I’ve tried with test accounts:

  • Creating a new offer for annual does not work (because they are paying)

  • Cancelling the current monthly subscription (only a couple of weeks old) does not work (presumably because they are still seen as a paying customer)

  • Signing out does work, but I have not yet tested what would happen if I used the same email to subscribe to annual.

I am hoping to find a better solution than asking customers to cancel and then sign out.
If there is a better approach please let me know.

Thank you!