Don’t want to sign warning letter

I started a new job 6 months ago in home care marketing, and have already gotten a PIP, warning letter, and now a “final” warning letter that cuts my commissions by end of month. This industry is new to me, but healthcare isn’t, as I’ve been an executive assistant for 25 years. This was meant to be a career change, but it sucks - the job itself is best when interacting with seniors. Dealing with two intense and harsh bosses is the worse.

Tomorrow, I have to go in and sign this latest warning letter, but I don’t agree with it. The training hasn’t been great, there’s a lot to learn, I’m working an entirely new territory in Boston with top notch places, it’s highly competitive, and I’m a rookie. They want 20 referral numbers a month, and I’m not there.