I had a bad experience with Xapo too. At first everything went smoothly until they decided to make an update.
In the next couple of days, all Xapo users will begin to pay the miners fee themselves in order to send transactions out of Xapo.
Does Xapo allow you to choose how much in fees you pay?
unfortunately no.
The problem is that you can't choose a custom fee they only offer two choices "a standard or high priority fee".
I don't use xapo wallet and so I would give you some options and if suitable try it at your own risk. See whether the transaction is free from xapo to another xapo wallet (some wallets support this feature). If it is supported then sell Bitcoins to someone who needs it.
Xapo to Xapo payments are free of charge, but if you find someone to buy he will buy at a low price and the problem will not be solved.
Xapo fees are too high even before the nework congestion.