What to do if the outlet melts?

Good evening men! I live in a one-room apartment. In the common corridor is an electronic meter. There are 3 automatic machines on it: 25A (5 outlets), 10A (lamps), 25A (separate outlet for a boiler and a washer). This separate outlet at the junction of the aluminum wire (old wiring) with a copper 3-core wire of 1.5 mm square. almost melted. What need to do:

a) output from the meter a separate wire of 2.5 mm square. to the washer, but to the old boiler outlet?

b) change the wire to the outlet from 1.5 to 2.5?

Thank you so much for the answer.