We are sorry to hear the low-medium pile chair mat has not performed well for you. Mats can take a couple days to embed into the carpet, causing the wheels to dent between the cleats. Please try walking over the mat intermittently or placing a heavy object over the cleats to help them embed into the carpet. This should take care of the sinking you've experienced. If your chair continues to sink into the mat, please contact us at customersupport@dimexcorp.com. Again, we apologize for the frustration and hope we can help out.