The same happened w/my RB Pidge. She was 20 when I had her shaved due to so many mats. The situation w/her was that she was so old and stiff that she couldn't reach certain parts of her body in order to groom herself and she DETESTED being brushed and groomed. Like you, I kept up w/the mats as best I could until I finally relented and had her shaved. She felt so much better after that and lived almost 2 years longer. Because she was so old, her grooming/shaving was considered as surgery. She was put under anesthesia and after it was all done it cost $680.00! Lesson learned. As soon as I notice a mat, if I can't get it out, Specs will go to the groomer since he's my only longhair kitty. So don't feel bad. It happens.