Order cancellation

I ordered swimwear online, to be collected at a branch. After ordering I realized I would not be able to return swimwear, should it not fit. I then got the opportunity to try on the specific item in a store and realized it was not going to work for me. By then I had received the message that my order had been shipped, but I have not heard anything yet with regard to collecting. I emailed Miladys, explained the situation and asked if the order could please be cancelled at this stage, but the request was point blank refused. So I am not going to collect the order. I guess by the time the package is sent back and it comes to refunding, they will decide it is swimwear and may not be returned, although it will still be in the unopened package?