There is a plastic piece on bottom of radiator by hose hose that has melted so it sprayscoolant and overheating

Sounds like it could be part of the radiator, the drain petcock, which allows you to drain the radiator of coolant. If the plastic tank around it or the petcock itself is faulty, then you can have a leak like this. I'd recommend a first hand inspection at a shop near you: Use this link to find some shops near you that can help with your concern: www.repairpal.com/repair-shops