I've seen a couple of Reddit posts calling them a scam, but their team actually replied to most of those.
Some scam accusations also look to be a little bit embellished, not sure what to think about it.
I agree. The thing that rightfully annoys people is that most services don't know how to properly run a business, likely because of inexperience, but that doesn't automatically makes them a scam.
On the other hand, we can't entirely discard to possibility of something shady going on here, Wirex is not a reputable business as Coinbase or Poloniex after all (especially the latter had to deal with a lot of account blocks).
Their system is crap, currently it is fixed but in whole December, when I logged into my dashboard, after 5 minutes, suddenly Chrome browser was consuming 8gb+ RAM and 99% CPU.
It's quite similar to what happens when there is being browser mined. Not saying it applies to your case, but it is suspicious. Does the same happen when you visit other sites?