I’ve recommended a friend who’s used my referral link and has signed up with bulb but my account says I’ve no referrals has anyone any idea why?

The referral likely hasn’t worked properly for whatever reason. Ask your friend to get in touch with Bulb with your name, referral link and post code and request that they add the referral manually. Assuming that Bulb are happy to do so, the credits still won’t be added automatically, so they might need a nudge when the switch completes.