Disappointed client

I purchased a pair of sneakers on sale on the 30th October 2020, and the debit was collected immediately and was advised when my order would be ready for collection, only to get an email the 31st October stating my order has been cancelled due to an Inventory Error, and that my refund will take upto 5business days! I am highly disappointed and dissatisfied as their client service response was very robotic and not at all helpful! For such a big online retailer, they really don't care much for their clients' satisfaction!