My inexperienced view is:-
1) What did the original contract say i.e. have they moved the goal posts?
2) If yes to the above, well IMO such changes cannot be unilateral without a renegotiation of the monies to be paid.
3) Do they mean RAW or just unprocessed TIFFs
4) If they really mean the RAWs that is in effect asking for an assignment of the copyright as they will then possess the "originals".
5) read #1 above and repeat

In the case of #2 and #4 then based on other such posting I have read about such 'demands' depending on the type of imagery and how valuable they are to you as the author the price should be between 4 to 20 times the originally agreed prices.
Are they aware that to achieve the sort of results that they commissioned you to create that you producing blended (HDR?) images that are the result of your expertise & your creative style?
Best of luck coming to grips with what sounds like a "high maintenance" customer!