Question

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Dissappointed
I’m writing because I want to share my dissappointment with you about my new shoes and the treatment I received in a famous branch three weeks ago.
I bought shoes, which were on sale. I tried only a one shoe on. It fitted me and I felt very good in the new shoes. I took them. When I was at home I noticed that once of the shoes is bigger. I check up on a size of shoes. Both shoes were the same sizes. I returned to the shop next day and I wanted to change my shoes. But a shopgirl told me that she couldn’t change these shoes because they were on sale.
I showed badly marked siezes. She said to me that it was my fault because I haven't tried both shoes on. He behaviour was crass for me. I think that they blundered.
I want to change my shoes or get a full refund. I don’t have a lot of money. On the other hand what will I do with two different shoes? It will be uncomfortable.
What shall I do? Should I complain to the somebody? I’m very angry, so I can do everything. I work hardly to earn Money. Every penny counts.
I will be grateful for your advices.