Phone Company Incorrect Information - 3 Years On

thenugget2018

Recently I have done a check of a credit file (one of the lesser used credit reference companies), and found that a well known telephone provider that provides Telephone, Internet and TV, has left an account open on my profile for the last three years. I have found an email that confirms that they should have closed everything down and remember the service being stopped as I was still at the property, as it was still the last week of my tenancy.
The Credit File shows that I have been doing payments and that I am up to date (with the account registered at my own address). Nothing appears on my bank statements. All bills were up to date when I left the telephone provider, as I had to pay an early termination charge which is listed on the closure email.
I have spoken to somebody (three people on different days) at the company who has said that due to a data integrity issue the account can not be closed and this needs to be escalated.
I have been a victim of ID fraud before and am worried about post of this company going to my old address.
One of the representatives of this company I spoke to said not to worry, these things happen, no harm done and they will sort it. Have been waiting for three different phone calls, nobody has rung yet. Another member said this happens quite often when somebody tries to open a new account and do not follow through with it. (which I have not done after leaving them 3 years back).
What should I be doing, is there a breach of rules for Ofcom, Data Protection, FCA? Any advice would be appreciated.