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To disable autorenew, provided you are logged in under the same username account that purchased the upgrades go to > Store > My Upgrades and click the "disable auto-renew" link.
Also provided you are logged in under the same username account that purchased the upgrades, you ought to be able to request a refund from your dashboard > Store > My Upgrades
WordPress.com provides a 30-day refund on all upgrades except Domain Registrations, Domain Renewals, and Guided Transfers.
Note: It takes from 1 - 2 weeks for the refund to be received.