Was the guide I posted no good to you? Please take no offence as none is meant - but your daughter must be entering something incorrectly to be prompted for exchange server details, unless fasthost use an exchange server for their advanced email accounts? Actually I've just reviewed their sales website and they do have exchange based email accounts on offer.
Mac Mail changes it's options dependant on the users previous input. It can also check with the mail server based on the user previous input to see if the server can handle POP3 or IMAP. Looking at Fasthosts it looks like the advanced account may only be able to use IMAP (Based on their example in the article above). It could also be something to do with port configuration - but that's a longshot as the ports usually change based on the users input.
If you want my email to get in touch easier when you're at your daughters MacBook then send me a PM and I'll gladly share it with you. It wouldn't even phase me to connect remotely using TeamViewer to help you solve the issue, should you be willing to trust me of course!
No worries. I'm a fan of POP myself and as your daughter is a paying customer I belive they should be providing a much better serivce; telling you to use IMAP is not customer support but a weak work around. I personally would stand my ground and strive to have POP3 operational - that is however totally up to your daughter. Good luck with it!