Npower - Complaint to CEO - Who next? RESOLVED

In November last year, like a lot of people, I left Npower for a competitor. In order to understand the sequence of events that followed I'll put it in chronological order -

November 2013 - I leave Npower for a competitor.

2nd December 2013 - I received two "Sorry you'd like to leave us" emails from Npower.

5th December 2013 - I receive a "We're sorry - we haven't been delivering the service you deserve" email.

That is the last correspondence I had of any form from Npower until June 2014.

9th June 2014 - I receive an email informing me they've cancelled my payment scheme. No elaboration or any further information other than that.

19th June 2014 - I receive a letter, dated 17th June, from Gareth Pickles "Customer Services Director, Domenstic" informing me that as I may have seen in the media Npower has introduced a new policy which means they will not ask customers to pay for any energy they have not billed us for which was used more than six months previously.

I assume he is referring to comments made by Guy Esnouf, director of communications for Npower, on BBC 5Live where he stated that "Anybody who left us before December, so six months ago, and hasn't received a bill from us, then we are going to write that off". The letter ends by informing me I don't need to do anything and that you would be in touch shortly to explain things in more detail. To date that hasn't happened.

19th June 2014 (Again) - I called Npower at 14:23 and spoke to **** **** requesting clarification on the letter. She confirmed I'd understood the contents correctly, that I didn't need to do anything and that there was no outstanding balance.

At the start of August I was carrying out a regular check on my Experian credit report when I noticed Npower had made two entries dated 13th July stating that I owed Npower £62 for electricity and £40 for gas.

30th July - I called Npower and asked for an explanation. I'm told the familiar "someone will get back to you"

9th August - I called at 12:38 and spoke to ******. He assured me someone would call me back on Monday morning.

11th August (Monday) - I called at 18:02 and spoke to ******* as no phone call has been received. He didn't seem very interested and said someone would get back to me.

12th August - I decide to called the "Complaints team" and at 17:28 spoke with ***** ******. He listened intently and assured me he'd personally see that the entries on my credit report were removed and the fiasco would be resolved.

18th August - As it's been almost a week and I've heard nothing from Mr **** I call again as 11:15am and speak with ****** . She informs me that doesn't know if Mr ***** is in work today and what time he starts but someone will call me back before lunch.

Lunch came and went.

What the hell do I do next?