refund of input credit due to inverted duty structure

Sir I am ecommerce Seller and sell Footwear category on ecommerce portals like Flipkart and amazon For Footwear gst rate upto mrp ra 499 is 5% and more than rs 499 it is 18 % We purchase shoes from the factories of our own private label brand and they charge 5% in case of upto 499 and 18% if Mrp is more than rs 499 Now Flipkart and Amazon charges The sellers commission on which 18% gst is there It is input service for us and and we take input credit for this Now since we have majority of our sales at 5% gst so what is happening is our input credit is more than output gst and it is resulting in accumulated input credit which is being carried forward every month The amount is increasing every month and amount is huge Do we fall under inverted duty structure where refund is allowed as per gst law We also have some inputs like Polybag’s and boxes which are at 18 % and 12 % gst respectively but their amount is not that huge I have heard that refund of input credit of input service will not be given Is it correct