Calzedonia Tights Lost Shape, Became Loose in a Month

I boguht tights on CALZEDONIA. The tights I bought a month ago have become loose and the ankles and knees are in very bad condition. I only wore it 4-5 times. Because I don't have a receipt! They did not send it for review (even though I purchased with a credit card)! Are we paying all that money for nothing? I could have bought cheaper tights from other brands. Not sending it for review was to cover up the defect.