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.