Samsung Note 8+ abnormal speaker malfunction!

I would like to raise my outrage with Samsung. I have send in the same device, a Note 8+ in for repairs to the same problem. Everytime being fixed and not long the same problem occurs. This device is being advertised as a waterproof smartphone but why would a little sweat make the speaker malfunction? If it wasn't for the wonderful insurance that MTN offers I would have been bancrupt fixing this phone, this device was already repaired 4 time for the same fault. As this is a company phone I'm afraid very soon I'm going to be inasurable. I would like Samsung to please advise me how to handle this.