Spalj Construction Company d.b.a. Tjader & Highstrom

The Trenching co. went through my septic line;which caused the septic system to back raw Sewage into my Juccuzzi tub:also puting gray water into my laundry room:this happed on 3 seperat occations: the gray water was 2 additional times: They have refused to pay for the damages, saying I had to accept there offer of they would consider the case closed:not sure if they can do that leagaly or not, but I do know for sure that it is not right::Not sure what I should put into this,there offer was for $1000they upped the offer to $1500:then they sent it to a law firm?? [redacted] They wanted me to redo the same things I had already done:There offer was for $2000:I sent them a Bill for $5000 in July of 2012:they responded that I could take an offer of $3000 by Nov or they would not pay and consider the matter closed.The Cable co that the Trenching co had been working for:: [redacted] said they would look into it. Except to respond to emails form me they have not contacted me since Nov of 2012:when the ? trenching co. refused to pay there bill I said that I would add a late fee and charge 2% interst:this I waved for the firt two payments they were late:there bill now with fees and charges is $5780 if paid before the 27th of Jan 2013, after that it will be $5945:I know if I refused to pay my bills, there would be a fee and interest charged:Is my only avenue to sue???thanks