Unfair Policy

I find it very unfair that when you want to disconnect your DStv you are told because it is a month to month subscription I must pay for the full month and my debit order will go off as usual. When you join Multichoice and you connect mid month you pay pro rata yet when you want to disconnect you are told you must pay for the full month regardless. I am moving out of my current residence and have packed up the decoder for storage hence I want it to be disconnected yet I'm told they can only disconnect it on the 25 of September because my debit order runs on the 26 September. This is completely unfair, if I can pay pro rata when I join why cant I pay pro rata when I disconnect.