If you see another company's name listed on your bill, you have either a Community Choice Aggregation (CCA) or a Core Transport Agent (CTA).
A CCA is a third-party electric generation company. This means that this company is generating your electricity and PG&E is responsible for delivering it. PG&E can provide both of these services to most customers, but some cities and counties have elected to switch to these third-party options. If you live in such an area, you were automatically signed up for the CCA either upon moving into your home, or when the city/county enacted the program.
A CTA is a gas procurement company. Similar to a CCA, they provide the procurement portion of your gas service and PG&E provides delivery. These companies are optional; you were not automatically enrolled in this nor did your city or county vote to add this company.
Any questions regarding charges from a CCA or CTA, or to opt out of their services (return to PG&E bundled service), will need to be directed to that company. You can find their phone number on the page of your bill that details their charges.
More information about CCA programs and CTA companies can be found online through the PG&E website.