Difficult to exchange if you lost slip

It was difficult to exchange without slip I as bought from one of the stores in mpumalanga and wanted to exchange ,the manager of total sports noord Johannesburg told me I must remember date when I bought my sneakers and the store as she cannot be able to exchange and if I want refund they won't help without proof of purchase and my aim was to exchange not to refund.because I was told that before I can even given a chance to go look for what I want I end up wanting a refund not as cash and I told the store does not have gift card I must go try somewhere else.i was very disappointed with the big brand like total sports (tfg) that I cannot be helped without slip and she started to call all mpumalanga store as if I am a suspect or I stole what I bought.will never ever bring my business to totalsport especially noord.