LAC+USC Medical Center complaint: blood infection

since August to October, my mothe, an 83 years old lady was in and out of lac usc hospital.
first, her blood pressure was low, her heart beats was low because of high potassium, she was admitted and treated and released after a week. a week after she was released i received a call from them to take her to any urgent care to get her blood labs because they found a blood infection while admitted, why did not treat her infection while at the hospital? fifteen days later i took her again because she complaint of leg pain, they found she need it a procedure to open her veins but they could not do that procedure there so she was sent home with pain killers her blood infection was not treated again. two weeks later i took her again because she was feeling weak and confused blood infection. while at the hospital i found they did a tiny scratch on her left foot. she stayed for over a week and i told doctors why you dont do the procedure she needs while she is here? well she was in and out of the hospital without receiving any care on her foot where the little scratch became an ulcer. i gave up on that hospital and i took her to another hospital where the next day of admission she got he procedure done and blood infection treated. the problems it was too late because she is about to loose her left foot because her ulcer got worse. my question is why she was not treated fairly having all her insurance current?