my iphone 7 speaker stopped working after the software update

My husband and I have two Iphone 7 (both around 4 years old) very well looked after that after updating to the latest version (14.4) of the software, speakers suddenly stopped working. We took both phones to an Apple store where they admitted that some Iphone 7 had the same issues as they seem not to support the 14.4 software version, but even then they refused to fix it.

As the Apple Robina (Gold Coast) manager said, she is one of the people that usually does not update her watch (as it's also 4 years old), which in my head, means that Apple may do it in purpose so we are forced to buy new appliances or they are at least dodge to not solve the problems they cause.

I refuse myself to buy anything else from this brand and I will do whatever I can to spread how terrible was my Apple assistance experience.