I ordered a 3 quarter bed mattress protector yesterday on the app, they sent me a single bed one instead

I ordered a 3 quarter bed mattress protector yesterday on the app, they sent me a single bed one instead. I cant get a refund on the app, and its very expensive. They want me to go into a store to return it, im disabled and cant leave my house, also I have no slip just the app as evidence so how can someone go for me? They should come pick it up if they sent the wrong product!