The issue with Wirex has always been the exchange rates. In my opinion, they employ a very dishonest practice of not disclosing that they have a fixed fee within their exchange rate. They advertise 0% fees for Crypto-fiat conversions but that's simply not true. Their prices have a stable deviation from live prices.
That's correct. But it's not a singular case. I've also had AdvCash card and they also had similar "issue" with the conversion rate.
On the other hand, I also consider Mistertango minimum top-up fee incorrect, since many newbies that didn't read everything have found out that they've lost most of their small amount they wanted to use to test Mistertango. Then, if you deposit the big amounts to avoid the min fee issue, you have to pay other fees just because you keep money in their business.
Or AdvCash, while advertising that everything is free, they used to have not only the conversion rate, also a "gateway" fee, quite pricey.
Right now Wirex seems to be on the lower area of the fees between the few card businesses and their card seems to work well enough.
There is, of course, plenty of room for improvement for all of them. As soon as more such businesses will start running, there will have to be a competition and the service quality should rise and the fees decrease.