function exchange(address user,uint256 _amount) whenNotPaused onlyCustomerService external {
  	
  	require((block.timestamp-CustomerService[msg.sender])>exchangeInterval);

  	require(_amount <= exchangeLimit && _amount >= exchangeThreshold);

    circulatingSupply = circulatingSupply.add(_amount);
    
    balances[user] = balances[user].add(_amount);
    
    CustomerService[msg.sender] = block.timestamp;
    
    emit Exchange(user,_amount);
    
    emit Transfer(address(0),user,_amount);
    
  }