Don't know what to do...

What is the name of your state? ca

My husband and I just finished building a house last year. It took us
2 years to finish building because of terrible plans we received from a
company in Or. The co. promised a complete set of plans that we could
turn into the county and go. Through out the building process we had
problem after problem with the plans. Everyone we showed the plans from
contractors to architects to engineers told us are plans weren't worth
the paper they were drawn on. We also ordered product for our house
from the company who drew the plans and rented some equipment. After 6-7
months of dealing with plan issues I confronted the company with the
problems and they said we could work something out to compensate us. A
few weeks later we were told by the co. that there was nothing wrong
with the plans. At the time we owed them $4100 for rental equip. The cost of my plans was about the same price and I had paid well over this
amount to get the problems with the plans fixed. I refused to pay the
balance until we could come to an agreement on the plans. They then
tried to put a lien on the house, but they didn't do it in the time
allowed. I got a lawyer to deal with the lien issue. I thought the problem was taken care of. This all happened now over 2 years ago. I now received a letter from a collections agency, who called and harrassed me and used obscene language when they called. The collection agency says I now owe $7100.
My question is what do I do now? Do I have any rights? Do I have any recourse in the matter? Does a subcontractor have a time limit on coming after me for money? I wasn't even going to go to the company and just chalk it up to a lesson learned until they started harrassing me and giving me attitude. They said they would do something to compensate the problems we were having, then just turned around and snubbed us. I have never been sent to collections and have worked hard to build my 700+ credit score and now it is going to be ruined because of a co. who screwed me over in the first place. Can I dispute the collection mark on my report and get it removed? I feel taken advantage of by a company and now they are trying to ruin us.
Thank you for any help you can give.

So what does your Atty who is handling the situation say?

We can not see your contracts, we can not see the plans.

Now the collection agency, yes they can ruin your credit rating and this can be listed up to 7 years on your credit reports unless you go to court and have a Judge make the decision and as part of that decision demand removal of the negative comments on your credit reports IF the outcome is favorable to you. If they get a judgment against you it can stay on the reports even longer and hurt a little worse with the scoring.

You could strike the first blow and sue them for the max in your jurisdiction in small claims court over their shoddy workmanship and delays caused by that work.