As promised, I'm writing to let you know how it developed. First of all, my faith in Avast has been restored! I am again a happy customer of Avast! Mr. Riley not only apologized for the treatment that I received, but also offered to refund the $299. He also mentioned that I could get a refund of the $179 as well if I would like, but I go back and forth on that one and will, I am confident, decline the offer and settle for the refund of 299. My son, even though his computer is now doing a few things it's never done before the cleaning and his Grime Fighter still does not work, his computer did get a cleaning, and for this I should pay. If I were to accept the 179 refund, I know myself well enough to realize that I wouldn't feel quite right about it.
I will eventually ask for the 29.95 back as well for the Grime Fighter that I purchased for his computer but still does not work, but I'm still waiting to see if a computer tech can somehow get it to work. It's a great product, I think, if it would just work...
I do still have some issues with my computer after the tech worked on it: my computer continues to post a full page message informing that I've lost connection to the page I was on, whether it's Netflix, Safeway.com, etc etc. It's the same error that the tech got over and over right before my computer stopped working all together. (My computer now works, btw, thanks to a great Tech guy.) I never had this message before he worked on my computer via remote access, but now get it constantly which is a true pain. I also now get pages, sometimes up to 3 or 4 at a time, of redirects. Anyway, this, I think, I will just have to live with now and get used to. However, I am still very pleased with Mr. Riley's response as well as the refund of $299.
Thank you again, Michael! Had it not been for you, Mr. Riley would never have even looked into this for me and I would still be a very upset Avast customer. Again, and pardon my redundancy, I am really very pleased with the outcome.

PS I still don't know if it was a third-party or Avast, but at this point, I guess it really doesn't matter.