Kasia: Hello! It's ABC, your favourtice Internet Service Provider! How can I help you? 
Daniel: hi! I got your service 2 months ago and while making the agreement you turned on some extra service for me, "safe internet" or something. 
Daniel: I wanted to remove it, but you said it's free for first month and I need to wait at least 3 days to turn it off. 
Daniel: So after a week or so I called and asked to turn it off at last
Kasia: Yes, "Safe Internet" service is an antyvirus we offer to all our customers with promotion of first month free.
Daniel: exactly!
Daniel: So I was checking my invoice yesterday and I noticed that even ethough I asked to turn it off, you still wants me to pay me for it
Kasia: That must be some mistake of our systems. 
Kasia: Please give me your customer number so I can check your invoice.
Daniel: it's 12345
Kasia: As I suspected, this is our mistake. 
Kasia: I am sorry about that. Your invoice is recalculated and sent, please check your email address. 
Kasia: Also the IT Department is informed about the situation, so the bug will be fixed as soon as possible
Daniel: Oh, that was fast, thank you
Daniel is lodging a complain with his internet service provider ABC for billing him for an extra service which he timely and according to the service agreement asked to discontinue. Kasia from ABC admitted it was a system error. It was instantly rectified and a corrected invoice was emailed to him.