Refund and collection

I bought x3 jeans in November and after purchasing i was told that two is out of stock and that they would only deliver one and was happy and i received my money and one order, the problem started when i wanted to fit my jeans only to find out that they are small and i tried to do a return online and kept saying that my order has not been fulfilled, i have been calling the call Centre and emailing with no avail, i just want you to collect the jeans and refund me its almost a month now im not getting any assistance.