I also have used and received excellent service from Mann In.
Always check three websites for contractors you hire in Fairfax County and Virginia:
Look them up on the local contractor complaint database:
http://www.fairfaxcounty.gov/consumer/complaint_history.htm
Local better business bureau:
http://www.bbb.org/washington-dc-eastern-pa/accredited-business-directory/
Va State DPOR licensing:
http://www.dpor.virginia.gov/LicenseLookup/