Free trial of "Amazon Prime"

I was offered a free trial period of Amazon prime for 28 days. After that period they take money out of my account every month.

So I took up the offer, then immediately cancelled, so I simply get the 28 days for free then it ends. However, they don't like that!

I clicked the cancel prime link and it took me to a page saying "Ian, we'd hate for you to miss out on your unlimited one-day deliver". Then gave me 4 options -- keep membership, extend trial, decide later, cancel membership. So I clicked the cancel membership, to get another screen imploring me to extend my membership for 7 days for 99p. Another 4 options exactly the same. I click cancel my membership for a 3rd time. Took me to another page wanting me to confirm my cancellation offering me 3 options, again keep membership, remind me later, cancel membership. Eh?? Already clicked it 3 times! So I click cancel for the 4th time.

At last success! I get a yellow triangle with an exclamation mark alerting me that my prime will end on the 9th November (doesn't that give me 29.5 days rather than 28 . .not complaining, or perhaps I should, they might give me another 28 days for free).