I don't think you "get" how serious calling CPS is. What you're describing isn't abusive. It's not good, but it isn't abusive in any way. The children aren't happy, that's not a crime. There are other ways to help the problem.
A change of venue in custody could happen. It takes filing a petition to modify custody only as it pertains to the physical living arrangements for the child. It doesn't take a lawyer to file. But after three years, you'd be hard pressed to find a Judge who would agree the child is in danger to remove her from her mother's care.
A GAL can determine the best interests of the child. An independent, uninvolved party can make home visits and assess living conditions then report those findings to the Judge. The GAL also inspects your living conditions, as well as interview the child and all parents/step parents/adults living in the home. This report is filed along with the petition to modify custody.
You can make an anonymous tip to the city's health and safety department, who would come to inspect the premises. If code violations are found, they'd cite the owner and make sure the violations were corrected. Depending on the severity, the house could be condemned and an eviction would take place.
You can contact the land owner directly, and state the rent will be placed in escrow until certain issues regarding the property are fixed. Again, that requires a filing through the Court system to enforce the non payment of rental as legal construct, not inability to pay.
The issue is, all because you don't agree how the child is being raised doesn't mean the mother is doing something illegal. Involving CPS only sets up a very lengthy investigation, and there's no guarantees anything would change.
Again, involving CPS is SERIOUS. It's not meant to be a catch all for divorced parents to get back at each other. Use the services only if NEEDED. What you're describing is a pain, but not to the point involving a legal entity that has the authority to place the child into foster care until a petition for change of custody has taken place.