Why is it ok for the cable company to take everything away?

My cable tv, internet, telephone provider is slowly taking things away from me (and others). First they decided that in order to receive certain channels, you would have to PURCHASE a converter box. Then, if you are old fashioned and want to tape something on VCR, that is now impossible--you must purchase a DVR for that. Then, every once in awhile, they have taken away channels that were standard when we signed on. If you want those channels, you must purchase a box for EVERY tv in the house. They just keep taking and taking and taking. Seems wrong.....even illegal!!