12 hour shifts?

Ok, so I have a question regarding 12 hour shifts. I currently work for an agency that works 12s. We work 36 hours one week and 48 the next and are on a biweekly pay period. That is a total of 84 hours. A question was asked regarding why our pay stubs only show 80 hours and if we are getting paid for the additional 4 hours every two weeks. The response given was that it was worked into our base pay. Now that it was brought up our pay stubs reflect 84 hours instead of 80 but our pay has stayed exactly the same. Essentially they just reflected what we asked on the pay stub but did not provide us with an answer as to if we are getting paid for those 4 hours or not. In return now our hourly rate has gone down. Example: say I made 40k a year for working 80 hours like my pay stub was showing. That put my hourly rate at 19.23 an hour. Now our new pay stubs show 84 so my hourly rate has dropped to 18.32 an hour. I was under the impression road patrol deputies were not salary and paid by the hour. I know that we can be made to work up to 171 hours in a 28 day period without getting overtime but doesn't the 4 extra hours biweekly have to be paid as straight time or compensated somehow? Very curious as to how I can determine if I'm getting that time added to my check or not. Am I missing something?