Hair oil inside my phone

About 3 months back ,hair oil went inside my Note 4 (model SM-N910G). It was lying on bed side table and the oil bottle spilled on it.Whole night it was submerged in oil.Oil went deep inside the phone.I cleaned it up many times with tissue pape after removing battery.Oil kept coming out for a month but for past 2 months it looks dry.The note 4 is working very well Except the earpiece is un audible.(even after oil spill it was working)The speaker phone works very well and so does headphone.

I took it to Samsung service centre and they gave me estimate of $550..which was shocking..They said the oil is deep inside the phone and whole of internal assembly need to be changed along with mother board.

As it is not covered under warranty i don't want to spend that kind of money.

Do i have any option to just replace the ear piece from a non Samsung repair shop?

Can oil inside cause more damage in future?Can it be cleaned at home after opening?

Since it is working perfectly (except earpiece) i am using it as my second phone(i hardly need to make any calls with this phone).Should i keep using it that way ?

I am confused.I need help..