As a chronic pain patient this is very upsetting and sadly familiar.
The effect of cost cutting is not the cost of the drugs it is about how many staff they have, so many wards are woefully understaffed it leaves both patients and staff in a very dangerous place.
Post surgical pain management for people who suffer from chronic pain is very difficult, we need more then other people because our bodies are so used to high levels of painkillers, this is why before we have surgery (as long as it is not emergency with no time to plan) we see the pain nurse and make a care plan, for that care plan to be so badly ignored is horrific and then the refusal to start putting it right is as you say, inhumane.
One of the worst ones for me happened about 10 years ago now, a care plan involving a mobile epidural was drawn up and agreed pre open gastric surgery. At the time this type of post surgical pain management we unusual so I was moved to a ward that claimed they knew how to deal with it and were happy with it. I woke from surgery in agony, the ward had no idea what they were doing and refused to call anybody to sort out the pump and dosage. Finally mid morning the next day the pain nurse came by to see how I was doing, the ward had not called her, she was horrified, the pump was set on the lowest possible dose and had been left rather then being turned up in small increments until my pain was controlled as was meant to happen.