Mr price home poor quality curtains *******

I bought 4 curtains for my lounge and I used them for a little over a year. I moved so I packed them away for another year. Now when I want to used them I took them out and the lining has turned yellow. So I washed them and they are completely ruined. I sent an email and got no response. I called customer care and was told its over a year and I don't have a slip. Do you wash your curtains all the time? How was I to know I must wash them so that they get ruined while in the warranty period? I got so many compliments on how beautiful my curtains are, but I can't pay for new curtains every year, because I can't wash them as they will get damaged. I also purchased purple bedroom curtains which have lost color due to the sun. Never again. All that money down the drain ****erally) because I don't have a slip after 2 years, what about responsibility for your quality?