Actually, if you dig into the Ts & Cs, the limit is 1GB a month. This is a big difference from unlimited, but not unreasonable since it’s an ok price. Why not just be honest and say it?
Actually, you have 5000 minutes of skype-to-skype calls. This isn’t bad, but they don’t make it clear that they mean skype calls only (no skype out, i.e. no calls to real phones included).
Actually, you have a hard limit of 10,000 messages a month. This is plenty, but by this point, you are likely to feel very suspicious of the asterisk. What’s silly here is that the X-Series package is a pretty nice deal by UK standards. There’s no need for all this cloak and dagger stuff. Good, honest simplicity would get them a lot further.