I'm unsure why E.On Next felt the need to lie about the reason for this credit as their statement can so easily be discredited by viewing Ofgem's website, but it sums up the company and its culture.
I base this on two experiences of E.On Next, the first one was around getting a working smart meter, they refused to sort it for 2yrs, until i took my complaint to the Ombudsman, who found against them after a drawn out and at times, painful complaints process, but the customer service rep who finally dealt with it said it should never have gone to the Ombudsman, it should have been resolved long before it was escalated.
The second was when they recently decided to increase my Direct Debits because I was apparently using more energy than my DD covered, this decision was made using inaccurate data, which I contested, providing the actual usage data from their own website, I was away for 2 months, I also confirmed that I have solar panels and am not using gas for heating as it was now summer, I asked for a call back to discuss as I was abroad - their 0808 number doesn't work from outside the UK - they didn't bother calling me, I chased it up on my return and asked for a manager call back, i never received one, instead I got a deadlock letter, so I cancelled my DD, paid the outstanding balance and will be moving to another supplier this month.
My recommendation to anyone considering moving to E.On Next is to complete your checks on reports of their customer service before signing the contract, the sign of a good company is not that they never make mistakes, it's how they fix them that matter and in the case of the £8 credit, they shouldn't have waited until Ofgem ruled against them to admit they'd been wrong. Buyer beware.