Persistent Sewer Line Backup

I have lived in a townhome at Cedar Place in Lakewood, CO for over a year. In that year, my (once finished) basement has flooded with raw sewage 6 times. The problem lies in the sewer line - the responsibility of the HOA - which does not have adequate drainage to the main line. According to public records and HOA meeting minutes, this problem has existed for over 7 years. Each time, I called the HOA Management's after-hours line, wait hours for an emergency plumber to be deployed and go through the process of moving everything out of the basement, waiting for a team decontaminate and rip up carpet, flooring, etc. This last March when it flooded I had a tenant downstairs. A restoration crew hired by the property management company tore all the drywall, carpet, flooring, and any appliances/fixtures in the affected area. This was all done without my knowledge or consent while I was at work. I was told by the HOA and property management company that their insurance would not cover the damage as it is "studs-in", so I was forced to file a claim with my homeowners insurance. My insurance has skyrocketed and I worry they will drop me from my plan as it is the third claim I have had to make. I have gone down all the avenues I know how, including hiring a lawyer to write demand letters to the HOA in hopes of getting a plan to fix the sewer line. The HOA's legal counsel refuted claims. The HOA continues to kick the can down the road, despite 52 members of the HOA paying $275/month for services they are not providing. It is just me in the home, I used to rely on the income of a tenant to help pay my mortgage but I am now out of funds since the basement is once again, flooded. I feel rendered helpless and feel this is in an injustice to the homeowners who just want to live in a home free of constant sewage floods. Any advice is welcome.