My mom's copay jumped 3x after her insurer changed tiers

My dad had the same thing happen with his insulin last year, except it was worse. He's on Medicare Part D and they moved his long-acting insulin to tier 4 out of nowhere. Copay went from $35 to $110. He didn't skip doses though, he just ate less food to make up for it. Bad idea. He ended up in the ER with low blood sugar because he was trying to stretch the insulin. Took me three phone calls and a fax from his doctor to get it fixed. Took eight days. The worst part was the lady on the phone actually told me I should have checked the formulary in November. Like anyone does that.