Adidas what a sore disappointment

I have never experienced such disappointment in an online store which is such a big brand Adidas stores is really just nonsense. I bought a pair of shoes for my child in June online and unfortunately the size doesn't fit her therefore we needed to facilitate a return to get the correct size after all the the procedures and them confirming that the shoes will be collected nothing came of it. I then made a call to customer service and still nothing happened then I went to Atterburry value Mart and they said since it's not in their stock they cannot do an exchange at that store this goes for the Menlyn, Pretoria central,Wonder park mall, and the fenedale store these are stores I have visited with my time and effort and petrol I went to these stores with reference from each of them saying that their system is saying that they have it in stock and every time I get there no help I always have to go back with the shoes at this rate iam frustrated with this if there's anyone who can assist please do help me at least get a refund. IAM so heartbroken I never thought that I could experience such bad service from them even the staff none of them are stepping up to help or to come up with any solutions.

Regards Miranda