My 94-year-old father has end stage arthritis (bone on bone) in both shoulders and needs pain medication at certain times. How can I get the facility to follow this?

My 94-year-old father has end stage arthritis (bone on bone) in both shoulders. His primary care physican has prescribed a pain medication for specific times during the day and night 10 and 4 every six hours. The facility he is in cannot get their computer to accept these times so they have changed the time to 12 and 6. This isn't working well as Dad is a worrier and stays awake at night waiting for the medication which has been late on occasion. I have tried to get them to go back to the time prescribed but they keep blaming the computer. The computer doesn't control access to the medication as I have seen them take it out of a locked container. I think it is just a bookkeeping type of reminder. I am frustrated and don't know what to do to resolve this issue.