4 people have ordered sim cards over the last few months and not one has been activated
I suspect that's partly due to incomplete information being given in the promotional material.
They're frequenly advertised to imply that a free member sim has £5 credit on it. That's not true. A free member sim has no credit and only gets the £5 bonus after buying £10 in credit or goodybags. When they find out they have been deceived and must "pay" to get the "free" bonus credit, they immediately lose trust.
I suspect that if all promotion (including member banners) was strictly vetted to tell the whole truth, the number of requested sims would go down significantly -- but the number of activations might go up slightly because the recipients would be getting what they expected.