With corrections:

Today I went to the shopping center with my father. He decided to buy a smartband that cost only 19€. I recommended to him that he open it inmediately, but he refused.

When we arrived home, he tried to remove the band to charge the device but he couldn't, it was too tight. I tried to but I couldn't remove it either, so he decided to ask for a refund. The shop attendant tried to remove the piece but they couldn't get it off either, so my father got his refund.