Elanic - Delivery and payment receivable issue

I am a reseller and i have sold one kurthi to one customer via elanic online selling app. The kurthi is delivered to customer on **th of july and customer has paid cash on delivery. But, elanic is not accepting the same and denied the status and they are telling that there was an issue with logistic partner hence the item is not picked up from my place even after customer has already received the iteam. There is no support from elanic customer care and every time they say the issue is escalated. i have submitted all relevant documents to them which i received from courier partner and customer who has received the iteam.