The call dropped in the middle of a parking transaction. What should I do?

If you were in the middle of a call and you did not confirm the transaction, then it did not commence. If you already confirmed the transaction, then it has already started. You can always check your parking status by going to the "Live Parking" page in your personal account. If the transaction started, you can use that page to end the transaction when you need to do so, or if the transaction hasn't started, you can use that page to activate it.