ios 8.4 update requested .... how do I update to ios 8.4?

I'm stuck updating iPhone 6 to ios 8.4 for a couple of days 😮. I've tried switching off and on, hard re-setting and variety of forums which suggest removing the beta profile (which I don't have).

Available capacity is 22.9GB

Version is 8.3 (12F70)

What's the solution?

Thanks in advance.🙂