Correlation ≠ Causation
While there may be lots of smoke, is there a smoking gun?
Do we know the outage is related to any of the AWS related service or is it impacting internal legacy infrastructure and applications and is that legacy a major factor in the spread of the problem?
I'm not defending Travelex, AWS, DevOps or Legacy, just pointing out that at this point I don't believe there is clear enough detail to laugh blame at any particular business decision or technology choice. There are things we can tut at, but tutting is not a good stance.