You Use plug sockets is low Quality ,or You use for Big AMP capacity,the sockets will Burn if use big capacity than socket,pls check your plug

Maybe you have a bad earth!! I would ditch whatever you are using,before you fry yourself!

I'm using a heater and I'd rather fry than freeze to death.

I've seen sparks come out of the sockets before. The way that I solved that was to turn off the power on the power cord and then put your plug in the socket. After that you can turn on the power and no sparks should fly out then and there shouldn't be too much melting going on. What is the cause of the melting? You have to find that out first. Is it near something that burns that can cause it to melt? 

chinese standards has got no switch for each plug point.. its always on.. unless you want to go to the main board and disconnect the MCB.. thats complex... so to live with this system.. 

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so make sure equipment switch is off when you plug in... so that no current will flow.. so no spark. eg. light should be off... iron box / heater etc should be switched off

Believe me, you would rather be cold than to be electrocuted by a high-amp device like a space heater. This is a bit complicated to be addressed over a forum, but you need a visit from a competent(licensed) electrician.

simply you are drawing to much current

Where did you get the heater from?

If plugs melt, The answer is simple your have either a short circuit or you are putting an item or items on the circuit which is demanding a greater amperage than the wiring can deal with

If the room where you are using the heater has an A/C unit, unplug that one and plug the heater there.  At least in my apartment, normal plugs are on 10 to 15 amps breakers, each A/C unit has either 25 or 30 amps breakers.  The wiring should be of higher gauge also, so heater should work better.

If male plug at end of heater wire also has loose terminals, it could heat up badly and help in the melting.