F’ing Septic Tanks

Just venting, if you guys have any advice I’ll take it. Bought a house 18 months ago, been having problems ever since. Every time we get a good rain it floods the septic tank. Can’t shower, flush toilets, wash clothes etc. for days after. Had the tank pumped, then had a good rain a week later filled the whole tank just the same. Previous home owner had a new leaching system installed, but the bastards didn’t disclose they were still having problems. I spoke with the company that installed the system just 5yrs ago...yeah they suck, also the county inspector is coming out tomorrow he was the one who signed off on the inspection. I have the feeling I’m screwed on this deal. I’m also going to call the VA, seeing that it’s a VA loan to see if there’s some sort of homeowners protection for nondisclosure. Cheers!!!!