Information needed about better protecting account.

In the past 5 years, I've had  my ISP BILLING  information stolen twice, and it was most definitely from this site, once after a controversial post (he threatened me, then later, the billing info was compromised), and once again later. And the passwords are NOT the same for this site and the account information for the ISP, in fact, I changed them both after both incidences.

Computer is clean, and I use malwarebytes and Kasperksy, both are fully up to date and functional.

The only reason I'm bringing this up now is because it's getting close to an "anniversary" of sorts where it usually happens.

Any ideas?

Thanks