Bad Quality Jeans

I bought a pair of jeans December 2012 time for £25 which I believe is expensive when you can go to h&m and new look and get cheaper jeans! At first I was very please and they weren't the perfect fit but fitted to a good standard!! But within a few months I noticed the stitching to loosen around the knees, and within 6 months of owning these jeans they have gained multiple rips. When I buy jeans I buy them to last or until they have been outgrown, as in my past experience with other retailers jeans. I have bought jeans from Dorothy Perkins which have lasted 5 year plus that still fit and have a small rip near the pocket which I purchased for the same amount of money.I am very angry with the quality and ADVICE no one to purchase the jeans as they are a waste of money for what you are buying. It is a shame because I love the design of the clothing, and even have friends that have bought tops and jumpers that have gained rips within months.