I tried to apply for a £6.00 sim only today and was declined on their credit check on line and also when I rang. I have never had a refusal in my life . I was referred to Experian so checked Experian and Noddle both show maximum score so the problem is with Plusnet. Warning applying for credit many times even for small items counts on your score so my advice is don't apply for one of these as even an incorrect refusal could have an impact on your score just go elsewhere.