We hired Stanley Steamers two months and we're not pleased with their service. They rushed us to do other rugs to clean which we thought was a deal ($99 for a whole house) after cleaning one-room carpeted and ended up paying $299.
Next time, we'll call Coit.
Ask bunch of questions and read fine lines in their paperwork(s) before you sign and the service!

The last time I deep cleaned my carpets I did it myself by renting a steamer/deep cleaner at Home Depot. I got a deal where I had it for the weekend, so I was able to do the high traffic areas twice.

If the carpets haven't been deep cleaned, you might want to consider going with a professional company and then doing it yourself a month or so later, because the first time will get most of the dirt up, but not all of it. Doing it later will probably then get most of it.

My new house has carpet and we can't replace it for awhile either, but, we're going to get a rug steamer/cleaner so we can clean it ourselves frequently, hopefully making it so we won't have to have a professional or rent a professional cleaner more than once a year.