Failure Demand is rife and built in to

I've just made two phone calls, to two different phone companies, with the intent of canceling services for which I am paying, but which I not longer find useful. The numbers I called are those published on the most recent bills received from the companies concerned. In both cases my call was put into a queue after I had had to navigate one of those 'press 1 for this, press 2 for that, etc' selections. When I finally got to talk to a human operator, I was informed that "we can't process that request by phone, we need you to write or email something to us". Hence, in the first case I was given an email address… in the second I was directed to a website in order to find the relevant email page!

So, instead of handling the customer's request, both these companies, respectively Vodafone and BT, have built failure demand into their systems. This wastes the customer's time and increases the costs for the organisation. It also reduces any residual feelings of customer loyalty.

Why do people do this?