Discovery Insure
Arbitary change of excess without agreement

So my wife recently had a small accident where another vehicle drove into and smashed her mirror. I submitted the claim to discovery and upon acceptance of the Claim was informed that my excess was R2750. After explaining that my policy's excess was R2000, I was told that a document was sent to all policy holders in June advising of an increase in excess. I never agreed to increase, written or verbal and have never heard of an insurance company increasing an excess except in the case of excessive claims and even then it's the premium that normally gets increased. One of the reasons I agreed to the current insurance was because of the flat rand value. To claim and now find out that this was changed without my knowledge is unacceptable behavior and to cap the issue, the agent dealing with the matter couldn't be bothered about it.