BAD RETURN POLICY

I have a problem with adidas online shopping,I bought some items and they delivered on the 10th of jan only to find that they delivered a bigger size.i then went to the website to request a return and they sent an email saying they will collect on the 14th it's been 2weeks now they haven't collected the item,to make matters worse is the fact that when u sent emails they dont respond when i call they tell me someone will collect the next day. I dont know what to do now..adidas dont take care of their customers,I dont understand why I should now struggle when in their website they put return policies and they dont follow through.as of now I'm sitting with a R900 dress that's two sizes bigger.