Low signal and microphone after dropped to water

Hi,

I have an Iphone 5s. I accidentally dropped it in water in my dream( don't ask how) and it stayed in water for at least a few hours(maximum 8). Fortunately it was in an Otterbox Defender, which saved it from an immediate death. Everything works perfect except from two things: there is low signal( 0-2 in my town(in bigger cities it raises to maximum) and the mic during calls is not working( with a microphone connected as well). 2 men tried to repair it, but non of them succeeded. The first one was an idiot but the second one is a respected and good technician. I researched a lot, and I found that replacing the "lightning connector& headphone assembly" maybe helps. I asked the second technician whether he had replaced this part or not and he said yes and he said only a logic board replacement could help. I don't believe him. The logic board is too far from the speaker/microphone where it got wet. And, there is two things not working on the "lightning connector& headphone assembly". Do you guys think it worth buying one and replacing the old one? I