Cancer treatment is not an exact science. What works for some doesn't work for others. Blaming the doctors doesn't get you anywhere.
My wife had Chemo for lung cancer for six months, without a good result, but no hair loss.
Then they changed to a different therapy. Most of her hair fell out and her nails turned brown, and started to fall out, but at least the tumours started to reduce. When they paused the therapy, the cancer rapidly spread all over her body, and to her brain. We thought she had a couple of weeks at most.
Then they started immunotherapy. This requires a round trip of 300 miles and an overnight stay every two weeks, but within a very short time, all of her tumours started to shrink. She no longer needs painkillers (she was on Fentanyl patches, topped up with codeine tablets), and her hair is growing again.
All you can ever do is hope.