I contacted IRS by pure chance from the Yellow Pages while trying to find a supplier of used or old vinyl siding to repair a wind damaged panel. IRS happened to be working in my area and without any fuss they came over and checked out the problem. He took a sample, found the manufacturer and told me my siding is over 20 years old and no one stocks it. The manufacturer would make it for me but it would take 3 weeks. He recommended a repair and within two days had the problem fixed.
If you're looking for used siding, repair of existing siding, or new siding jobs you'd be well advised to talk with IRS. I was very happy with the speedy response especially, but also with the way the company handled my problem.