Has anyone been denied commission? If so, response?

When promoted, I was promised a percentage on any company I brought in. During covid I didn't say anything due to the company going through financial issues. I came off furlough and then 4 months later we went through a funding round and got a lot of money.

I then brought up my owed commission (As I didn't want to cause a problem due it being a small start up during bad times) and then I was told it wasn't a thing anymore.

I, being on furlough, couldn't risk arguing due to the job market.

Just wondering how others would react or what they'd do?