You said 2months pa lang ang battery mo, Have you checked the connectors on the battery terminals if maayos ba ang pagka higpit after you change the batteries?
Yes alternator can be repaired but first, do some checking on the wires and connectors from the alternator to the battery. You will notice also if hindi na nag cha charge yung alternator mo or dead na yung battery kapag wala kang makitang mga small bubbles on the batteries electrolytes. If you have something to jump start you car then you can also measure the output voltage of the alternator with a multi tester if it is producing any voltage to charge the batteries.