Redland Sports Co Ltd is a large sport retailer. It purchases ‘cricket bats’ for $110 per bat from Cricket and Accessories Ltd, a large importer of cricket bats. Redland Sports Co Ltd (a GST registered entity) plans to sell the bats at a 200% mark-up to its customers. In January last year, Redland Sports purchased 100 shelled bats. However, in April, it was discovered that 10 bats are default. Redland Sports Co Ltd returned them to Cricket and Accessories Ltd and obtained a full refund. 

Explain the GST consequences of this arrangement for both parties