"I have tried repassivating" With some do-it-yourself product? Or sending it out for professional acid dipping?
The DIY products won't do the same job as acid dipping. But either one is just going to work on grains of iron left by tooling, etc. which are the usual cause of rust on stainless that has been worked with tool steel benders, etc.
If your rust is because of bad alloy, the only way to beat that is by replacing it.