You have been given some good advice here. It is an excellent idea to have a groomer cut her hair so you can start over. This is important for the dog's comfort and your relationship with her.
After the groomer has trimmed her, begin regular home combing/brushing. I use a slicker brush, then a greyhound comb to make sure I can reach clear to the skin without any mats or knots. I use a grooming spray I made up of a small squirt of conditioner diluted with a lot of water. In the past I've also used a spray called The Stuff.
It's important to know that there is no product or brush that is going to make mats and knots easily come apart with no distress for your dog. When you are going through coat change the number 1 easiest thing for your dog is to take the coat short. The second easiest for the dog is to brush EVERY DAY. During coat change there really is no other humane option with a poodle. This is why so many poodles are taken to the groomer every 4 weeks, and why groomers shave a dog down if the owner has not been able to stay on top of daily brushing during coat change. It does get a bit better after coat change is through, especially for those pet owners who choose to keep their dogs in easy to maintain clips.
The poodle coat is glorious. How much work it takes varies in direct proportion to how long it is.
This length was easy to comb. We were about to go camping just prior to this groom.
This dog (poodle mix) has a donut mustache, and needs his face groomed most days. For him it's just a few swipes of a comb on face, ears, topknot. Takes about a minute. If you want a fluffy face on your poodle then ask the groomer for that. I like the mustache style because it includes a shave under the eyes which helps me keep his face clean. He doesn't get tear stains, but a lighter colored poodles will tend to show staining without regular care (and sometimes even with regular care). This under eye shave makes face care easy for me.
Best of luck on your grooming adventures! Remember to give good treats!