Leaving aside the ethics, it seems to me you may have some wiggle room based on the following.
From the Gambling Commission website:
Quote:
What are codes of practice?
Codes of practice are either:
social responsibility code provisions - which must be adhered to by all licence holders
ordinary code provisions – these do not have the status of licence conditions but failure to take account of them can be used as evidence in criminal or civil proceedings.
We have powers to take action against licensed operators who fail to comply.
Quote:
Ordinary code provision 3.5.4
Self-exclusion – remote ordinary code
...a customer who has decided to enter a self-exclusion agreement is given the opportunity to do so immediately without any cooling-off period.
From the Redkings Responsible Gambling section:
Quote:
If your account is closed due to gambling addiction, your email address will be immediately unsubscribed, your payment methods will be blocked and you will not be able to register any new accounts.
If a member of our staff notices any clues that a player may have a gambling problem, the player is contacted to make them aware of our Responsible Gaming policy. As part of the training process of all new employees, they are taught what to look for in players’ gaming activity to spot potential problem gamblers. They are also trained in communication techniques to use when speaking to a player on the phone or on chat who says they have a gambling problem. Players will be informed that they have the option to implement deposit limits on their account if they wish to restrict their spending to a certain amount or to self-exclude themselves.
I can't see anything in the Gambling Commission rules or Redkings conditions that require the words 'self-exclusion' to be used. In fact the Commission seems to want to make it as easy as possible to self-exclude. Having to use the correct form of words would seem to be too much of a hurdle to jump. Nor can I see any requirement to admit to a gambling problem. A problem gambler wishing to self-exclude may have difficulty admitting their condition to a customer service agent. Again, requiring them to do so, as opposed to merely asking for an immediate closure of the account, may be considered an unreasonable obstacle.
In your position I might begin by asking for a copy of the chat logs so that you can see exactly what was said, considering whether there were "any clues that a player may have a gambling problem", and, I think most importantly, asking for the authority for their assertion that you are required to use the words 'self-exclude'.