Contact SONOS, they might be offering some sort of repair option. One of the design goals of ERA 300 is that field repair is practical. That said, I don’t know if any organizations are geared up for this now. For example I don’t know if there is a way to purchase repair parts.

Here is a video that you might find interesting.

As stated on the product page, the Era 300 wall mount is stud mounting only.  You can't just screw it into drywall, it needs to be screwed into a stud.

I’m well aware of what it says on the product page and I haven’t just screwed it on to a dry wall. The bracket is still intact on the wall, the bracket itself has failed as it is of poor quality.  There’s always someone on a forum who likes to be be smart.

There are a lot of people who would claim that the bracket failed and leave out the part of how they did not install properly, or used a generic mount that was not designed for the Era 300.  That actually seems more likely than a bracket failing to be honest, since we are not seeing anyone else claim that the Saunus bracket specifically designed for the Era 300 failed them.  Always possible to have exceptions though. 

Hope you’re able to get this resolved.

The Bracket was built and designed for the Era 300.  If you look at the picture the plastic part where it allows the speaker to pivot up and down eventually gave way, not once but on two occasions. The independent shop where I purchased it from advised me to glue it. In the end I opted for a refund and have purchased a far more durable bracket. 

Wasn’t looking for criticism, just after advice. 
 

I would definitely contact Sonos about a repair/replacement, refer them to their “Listen Better” sustainability report if they don't ‘listen’ 

https://s29.q4cdn.com/969873633/files/doc_downloads/esg/Sonos-2022-Listen-Better-Report.pdf

Design for serviceability: Minimize waste through repair and recycle. This process seeks to optimize disassembly and reassembly processes to make refurbishment, repair and end of life recycling more efcient and sustainable.

Another key way to reduce the environmental impact of our products is to transition to regional repair and away from moving products that need servicing across borders. We began work on in-region repair in FY22 with a focus on products that only needed cosmetic refurbishment. Based on the success of that program, we’ll be expanding this initiative moving forward to cover more products to reduce our emissions and save on costs.

I have the same Sanus bracket and it is not make to take the weight of the ERA 300.  When you try to make them level, the slider that is on the speaker side, and the wall bracket just can’t support the speaker when you try to level the speaker.  The entire bracket bends, clearly not able to take the weight.  We swapped out our 5’s to have true Atmos, the brackets for the 5 were absolutely awesome.  These for the 300 are pure junk.