2 cellphone batteries swollen

I bought a Samsung Galaxy S4 about 1-2 years ago. About 6 months of having the phone, the battery became swollen meaning that my phone would switch off and restart at random times and wouldn't switch back on without it being on charge. I bought a new battery for R400 and about a year later the second battery also started swelling. I love my phone and I love Samsung, but its really upsetting that I now have to buy a third battery for the phone and batteries are not cheap at all.