I would be grateful for people's thoughts, guidance and advice on the situation that just occurred.

I was ticketed and confirmed on a flight and the flight needed volunteers, so I volunteered under the contract that I'd get $300 for being bumped. The gate agent figured out that he needed one person and VDB'd me (my reservation disappeared from the UA app and he said he had deplaned me). Moments later, he realized there was another flight was delayed that would result in a few mis-connections; As such, he didn't need me to bump anymore. He then put me back on the plane, in a different data and told me he wasn't going to give me compensation because he got me back on the plane. For what it's worth, he never handed me the compensation. Also, when he realized he didn't need me and would need to reseat me, he offered to give me $100 for the inconvenience.

Am I entitled to compensation for being bumped under the VDB agreement, regardless of the fact that I was put back on the plane? If so, what is the best strategy for getting that compensation?

Thanks in advance for any guidance and advice you are able to offer.