Best point of contact to lodge a complaint?

After being fobbed off/ignored by customer services and the billing department for a few weeks regarding being overcharged, I was wondering who is the best person to get in touch with to lodge a complaint?

The website is a bit vague and will end up with me contacting the same departments.

I would prefer to do it writing as there are a lot of dates and figures involved... and would like a record of any reply.

Thanks.

The complaint process is here. You can find an address at the bottom.
https://www.zen.co.uk/policies.aspx?page=10675

Hi rich_jtg,

We are sorry to hear you have had difficulties in interacting with us at Zen Internet. Please email [email protected], marking the subject field as a Complaint - we will ensure to pick this up and contact you.

Kind regards,
Zen Internet

You can always put your issues to the CEO if nothing else works:-

http://www.ceoemail.com/s.php?id=10544&c=Zen%20Internet

Just to update - finally got everything ironed out, but took over six weeks of pestering to do so.

The connection I had with Zen was faultless, but the customer service I received when leaving was pretty much the worst I've experienced... and I've been dealing with BT recently.

I would probably still be trying to sort out a refund if I hadn't been chasing them up constantly. Trying to get them to realise anything other than what is currently showing on their system, even if it was common sense or blatantly obvious, seemed impossible.

The illusion of paying a premium and thinking you will get a premium service is an illusion I won't be falling for again.