iPhone 7 software issues: microphone and loudspeaker not working anymore

I have been totally happy with my iPhone 7 for the 2 and a half years of using it. The battery life is good and the camera is great. A week ago, however, suddenly I began having problems making phone calls. The loudspeaker and microphone don't work: this much is clear because Apps with sound have no sound. I read everywhere on forums online that the problem is known and if one has a particular model of phone, you get a new one in exchange. Problems starting happening with iPhone 7 back in March of 2018: apparently i have been lucky to have no problems until now.

The phone is no longer on warantee, and at the Apple Store they offered me a 265 euro credit towards purchasing a new phone. WHAT A RACKET! I am extremely disappointed in a company I have long trusted.