SPRINT - NEXTEL - BOOST - SPRINT PCS, SPRINT NOW NETWORK, SPRINT TOGETHER WITH NEXTEL ASL charges, Internet

I received the same letter today about the ASL (account spending limit) charge that Sprint decided they should start charging their customers because "everybody else does it".  That was the response I received from the lady in the credit department after I asked that the account spending limit be removed from my phone. She then told me that after 18 months that they would re-run my credit and at that time the ASL might be removed. 

The guy before her told me it was to help Sprint cover the customers that are running up their bills and not paying them. Heres an idea, don't give them spending limits to run up huge bills they can't pay. I haven't been late and pay my bill on time.

If they can change the contracts at any time with out penalty, then why can't the customers? I thought the point of a contract was to protect all parties of the contract, not just one side.