Consumer Fraud Company retained collectin agency for bill I refuse to pay due to items not received

Late 2011 I subscribed to ancient history DVDs. I signed up for auto-shipment so I received a package (3 DVDs in a package) once a month. Couple of months ago I received a bill for 4 packages. I had received 2 so I waited for a while for the other 2. I didn't get them so I went on line and paid for the 2 I got and informed them that I did not get the other 2 and canceled my subscription. Soon after I got another bill and asked to pay or they'd go to collection agency. I was quite upset so I listed all the DVDs I received, 13 in all, and listed the numbers on each booklet-case that contains each DVD. I also informed them not to threaten me with collectin agency or I will put in a complaint to BBB. I got another bill with a list of 19 numbers for 19 DVDs. These numbers are in 3 digits per DVD, and was instructed to look at the back of the DVDs for the numbers to match. I looked at the booklet-cases, I even looked at the DVDs to see if any of these numbers could be found. I couldn't find them. Now the numbers on the DVD cases range from 1 to 2 digits. Again, I waited to see if any of the missing two will be delivered. I didn't receive them so I just ignored the company's since I already told them how many I have received and the numbers on each DVD case. A couple of days ago I received a letter from a collection agency stating that they have been retained by this company to collect $125. and some cents; the company's was $122. plus. I have to respond by July 13th. I am livid and weary of what the collection agency might do if I refuse to pay. Has anyone ever been in this kind of situation before? I don't know what my legal rights are.

If you live in California, that state's law will govern.

But the caption says California company retained.... It's not CA company; it's PA company. How can I add info or ask advice on my first thread? I want to get some advice, comments or suggestions from members before I write to the collection agency.

Stand by. I'm sure there will be lots of info for you.

Respond to the collection attempt with a SIMPLE dispute letter indicating the debt is not valid because the product was not received. If it ever shows on your credit report make the same dispute to each credit agency.
Until they actually do Sue and obtain a judgment you do not have to pay a dime.
That said, review your original agreement for terms explaining what to do if shipment is not received and be sure you complied with the procedure and time frame. If you did not follow the instructions you originally agreed to you might find yourself paying for items not received.

Thank you for the advice. Unfortunately, it was one of those business card you get in the mail. I just checked it and returned it.