One of the offspring who, like me has been with Pipex for some considerable time, got fed up waiting for the (excellent) ISP to upgrade his £23 a month 512kbps service as promised.
So he reluctantly decided to ring and ask for a MAC code. He was immediately asked why he wanted to leave and explained the situation.
Instantly he was offered a 2MB service with a 30GB cap and, what's more, with a £5 a month discount.
He had no hesitation in forgetting about the MAC code.