Without being patronising SS, that's because it's convenient.
We found that when we used a broker in Bexhill for years, Green Finance (formerly Peter Shrubb), we just signed the best deal they said they had, and that was it done for another year.
I would emphasis that its worth shopping around...
That shouldn't be the case.
You need to get back to them and ask why it went up for Mrs SS, just because she is a house wife.
I go online to one of the comparison sites, and they urged me to put my wife down as a housewife, and the policy amount went down considerably.