How can companies alter contracts without your permission and you can't?

I have ever had 1 claim and it was a horror. It was a valid claim and Santam tried it utmost not to settle utilizing all manner of excuses and underhanded tactics. Long story short, in the end, as difficult as it was, Santam paid out. I wish I had the recording of when their representative phoned me and finally admitted defeat and that over a claim I consider peanuts but for me it was over principal. And here we are again, principal. I received a letter from Santam. They have altered our original agreement concerning cover over power surges. This without my consent and they state that it is now part of the new contract. Interestingly enough I don't see the monthly premium reflecting these changes. Surly if I lost cover in some respects which was used in Santams algorithm to calculate my original cover then my premium should come down not so? The contract was altered by Santam, I have lost value/cover, Santam has already proven to be ***** and *************. I dread the day I will have to deal with them again so where is the value? Just thinking out loud. I really really really miss Virgin Money.