Before we start, it is almost impossible to properly help you without accurate information. Buy this test kit, it is the industry standard. It will accurately tell you how hard the water is. Do you have iron or manganese in the water? If so, you need to get an accurate test for that as well.
Your resin may be bad and fouled with iron or other contaminants, resin does have a limited life expectancy and the exchange sites can become permanently fouled so capacity will be lower than expected. Cleaning can help, but that has a very limited affectivness.
Hard water leakage past the discs is common, but usually in chlrinated water supplies after 8+ years, on a well, the discs usually last significatntly longer, but they can definetly wear out.
Hope this helps