We can indeed see multiple transactions with the same amount for United Airlines. On our end, they look like normal authorization requests, so we are not sure why United is not able to process them. (more about authorizations).
Of course we understand that for such a large amount you do not want to wait for 40 days for the money to be released, but in this case as mentioned by my colleague, we’d need some proof from United that the transaction was not successful on their end and they will not try to settle this amount, for example some e-mail proof.
We would love to take care of the issue on our end completely as requested, as we understand you’re busy, but unfortunately if we would contact United on your behalf, due to privacy reasons, they will not be willing to share information regarding your transactions. We hope you understand that we also need to safeguard ourselves and need some confirmation from the merchant, as otherwise anyone can claim a certain purchase did not go through, spend the balance in their card, and then if the merchant later tries to settle the money, we’d have an issue. Normally merchants settle in ~1-3 days, but there are cases where it happens later, for example fully flexible / refundable hotel bookings, where the merchant may authorize the amount but only settle it if you end up staying. So this is why we ask for the proof.
The likely reason why the charge was made so often, is because some companies have a system in place whereby if a transaction fails, they will automatically try e.g. 5x more. This is the system of the company and not related to our system.
Blocking your card instantly from the app is one of the features we offer for your security. We do not recommend unblocking after, but ordering a new card if you suspect fraud. Moreover, you can enable instant push notifications or SMS messages for transactions, so you will immediately get notified when a transaction takes place, which is unlike a normal credit card where you may only find out at the end of the month if you receive your statement that unknown transactions have taken place (actually, for most credit cards authorization holds are even kept invisible and the amount is only deducted from your spending limit)