I just realised I made a mistake when I bought a non-refundable Heathrow Express advance online ticket, it’s meant to be for Heathrow to Paddington but I bought the ticket Paddington to Heathrow

does anyone know if the direction matters? If the barriers don’t open will staff let me through if I explain I got the wrong direction? Or have I wasted my money with this simple mistake

I did try contacting Heathrow Express, they said they will get back to me in 20 business days!