High cancelation fee

I would like assistance with dstv. Im paying R139 for access package, i had taken the wifi router adding to my package and then the price of the package increased to R306. Their data doesn't for even a week or better yet for 3 days. I have sent them that I want to cancel the wifi subscription and this is the message they sent me "please pay R1767 is due as a once off payment to cancel dstv internet".how is it possible that their cancelation fee is so high /expensive please assist me