Mycelium also doesn't support segwit, and that was another factor in my decision to ditch it. I could have lived without the segwit thing, but it's the fee that was the deal-breaker. It's too bad the developers aren't updating the wallet, because they could fix these things easily I would think.
I updated my Mycelium. Was using old version. Now they have slide option, where you can move lower fee to send.
Try to use the electrum on mobile they support segwit addresses and make sure to save your seed phrase because electrum on mobile there's no option to backup private keys.
Last time when I used Electrum mobile version, it was very laggy, now I don't have any issue with mycelium. If I can change fee than I am happy to use Mycelium.