Global,
The minimum requirements are something like being over 18, over 1.58m tall, fluent english, customer service experience, be able to swim 25 meters and be physical fit, some gcse's, I believe, and obviously the right to work in the UK.
Does your wife meet those?
If she does, she should go back to the application and have a good look that she ticked all the right boxes, just to make certain.
If really worried send an email and ask. She should make a point that she meets all of them and is worried that the computer which sent the automated reply has made a mistake. Always worth a try!
Good luck!