Charged for opting out of SMS marketing

[Olij]

I’ve recieved a text today from O2:
Hi. It looks like you recently sent your first premium text (SMS).
Just in case you didn't know, this sort of text isn't included in your tariff.
To check your charges and stay on top of your bill, head to My O2: <link>

This was for a text that I send to 6006 to opt out of adverts being sent to my by JD Sports (pretty sure I didn't tick any box to consent to that following that black friday purchase).

Now, ok, the charge was only 8p - but this seems messed up that I should foot the bill to opt out of sms advertising! 

Is the charge a mistake by O2 and if not who do I complain to?

[MI5]

@Olij 

The charge is levied by JD Sports.

It is they you should complain to.

[Olij]

I've used this before to opt out of advertising from other organsations and never received a charge - so I was wondering if it was a mistake by BT. Pehaps different shortcodes (the bit you text) can end up having different charges.

I have also written to JD Sports so I will wait to hear back from them.

[MI5]

@Olij 

It all depends on the company you are sending the text to.

They should be free but some do charge.

You could question it with O2 but they will probably just tell you that they are passing on the charge from JD Sports.