Mango Clothing Abuse

Mango has ruined my online shopping experience, bought clothes and one T-shirt couldn't fit me and asked for an exchange and I've been waiting for two months for them to come to pick up the T-shirt and give me a different size or money. I've emailed them numerous times all i'm getting is the automated response. I'm o over them. What is it that i should do with a t-shirt that doesn't fit me