Well the bill came today, and they've applied my discount only until the end of my contract (a week's time), where they expect me to pay full price for the rest of the time.
I've sent them a message pointing out all the embarrassing failures and lack of contact on their part, ending with "by your hand, all I require now is my MAC code or a discount of massive proportions".
If I'm moving ISP then, I will only pay until 9th June (end of my contract), and then they can cut my service until I join Sky.
(Plus, I gave an obviously fake alternate contact number, so the Indians will have to email me rather than make no sense and answer unasked questions on the phone)