Claim Specialists International - CSI Not paying sub-contractor, who now as filed a lien against our property. Denver Colorado

Claim Specialists International came to our door on 6/2/2008 saying they could work with us and our insurance company to repair/replace our roof if damaged from hail. The roof was inspected by Rick Buresh and we were told it had damage.
We checked with BBB and found that CSI had an A- rating and felt that this was a safe business to deal with. We signed a contract with CSI to repair/replace the roof and we paid $2000 down. In the contract, it states we owe no more than the deductible ($500) out of our pocket and our insurance would cover the rest. They finally repaired/replaced roof in November 2008. It turns out that CSI subcontracted to AVI Inc. dba AVI Roofing and Gutter to do the work. We paid the remaining balance to CSI on 1/3/2009. On February 14, 2009 we received a statement of lien on our property from AVI Inc. They state that they have not been paid. We immediately called Claims Specialists International, there was no answer, so we left a voice message that we received the statement of lien from AVI, that we had paid the bill to CSI in full and CSI should in turn pay AVI.
We also emailed CSI and AVI telling them this:
"We received a statement of lien on our property via certified mail on February 14, 2009. The company AVI Inc. dba AVI Roofing and Gutters says they have not been paid in the amount of $5064.13. We paid Claim Specialists International $5126.05 for the roof to be repaired/replaced and that is all we are going to pay per our contract. Please pay AVI their money to straighten out this problem. We will be contacting our insurance company and our attorney on Thursday, February 19, 2009, unless we receive proof in writing from you (CSI) and AVI that this has been resolved and the lien removed by February 18, 2009."
We did some searching after 2/14/2009 on the internet and found that CSI was given a D- rating by BBB on 12/18/2008 and there have been numerous complaints by mistreated customers recently. We read the contract carefully, checked out their business rating and thought we would not have something like this happen! What else is a consumer to do?

Beverly
Aurora, Colorado
U.S.A.