Paytm Mobile Solutions — partial product delivered and partial refund provided

I have ordered 2 Pairs Sparx Sandals on 17th April, 2019.One of size UK 8 and another o[censored]K 10 but Paytm has delivered me only 1 Pair of Sandals.And the delivered Sandal is duplicate as there was no size on that Sandal, So it was difficult for me to identify which sandal they have delivered to me as it was duplicate one. I have requested for the return and refund. The Courier person has asked me to return 2 pairs but I was not able to provide 2 pairs as only 1 pair was delivered to me.So I have told him that you know that you have delivered only 1 box of this size then how can I return 2 products. At last he has taken back that single pair and Paytm has refunded me only for 1 pair. Then I have complained about it to their customer care but still they have not responded me properly just only they have given me a reference no which is[protected]