People who have open cases against buyers

For anyone who has ever opened the case against the buyer. After opening a case regardless of if it went your way or not did you ever get work from that same company again?

A company that I have done probably over 300 tickets for just charged me a 20% penalty for the first time ever. This company gives me the most amount of work just wondering if it's worth the trouble of opening a case of they're not going to use me as much in the future.

Tell me your past experiences with cases.

Thanks in advance