Walmart complaint: shoddy shoes

bought sandals for my granddaughter,after 1 wear (One time)sandals fell apart,I tried to return was denied by cashier because child had wore shoes bottoms were dirty,spoke with managerwho basically said the same thing added it was a clearance item,neither one of them even took the time to look @ my receipt.
I called to complain phone number received an apology but was told its a decision of the store manager, my older granddaughter also works @ that same store store she’s a department manager ,when I told her what had happened ,she relayed to me it was odd about the manager because they currently don’t have one wondered who the cashier had got to talk to me. I feel like Walmart should have stood behind their product the product should have lasted longer than 1 time of wear how else would a sandal bust if it wasn’t worn ? how do you wear a pair shoes to a 4th of July cookout without getting the bottoms dirty? I’m currently not going to purchase anything else from Walmart because I have expectations of my purchases lasting longer in lieu of my recent experience it would be worrisome for me to try return something should I have a problem,I have been a good customer in the past but I’m upset enough to take my time money elsewhere, this isn’t about money It shouldn’t matter if somethings clearance or top shelf,if it falls apart after 1 use then Walmart should stand behind their merchandise .Thank You.