Help Ines with a plumber's skills: a septic backup

In July an inspector told me that my home has a septic backup. It's a safety risk for me and my two small children. The landlord has refused to act, and quotes of $310 are beyond us. I'm looking for a licensed plumber who may be able to donate a few hours or do the repair at cost. I can cover the parts, which I estimate at $15. The job should take about four hours. I'll make sure someone is home and will provide refreshments. I can share the inspector's written report on request. If you're a plumber and can help, or know a program that assists with this sort of repair, I'd really appreciate it. Please ask me anything in the questions section. I'll answer honestly and quickly.