Hissing sounds from charger and Macbook does not always charge

My MacBook is quite a few years old and has had this SERIOUS problem off and on for awhile. When I plug the charger in the magnetic part that connects to the MacBook often makes a hissing noise. It also sometimes illuminates green even though it is not fully charged and shows the symbol of being fully charged on the screen. It sometimes is plugged in and illuminated red yet the power amount will not increase. It often dies while plugged in. Overall, just totally chaotic charging capabilities. I purchased a brand new charger and battery. I have borrowed friends chargers and had it looked at by a reputable apple repair place yet they said nothing was wrong with the charging port or battery. Its crazy! I usually have to adjust the plug a million times until it gets just right yet sometimes it won't charge at all for hours! Anyone have this problem or a solution to it? Thanks!