Bad customer service

Bought boys track suit about a month ago, had an issue with quality of the pants, the top is still okay. Decided to go back to the store in Lambton where it waspurchased, but they refused to listen to my query since I had no price tag but i have the purchade slip, with dates of the item . Mind you this was only worn 3times washed twice, really disappointed with the service received at the store. They have just lost a loyal customer