Size of the watch strap

I purchased a new apple iwatch, and used the size guide to purchase the strap but it is way too big and hangs off my wrist. I am told by phone support I cannot return just the strap, I have to return the whole watch. But if I now do this the iwatch in my chosen colour and size is no longer available.

My closest store is barcelona, a plane ride away.

This is very frustrating, when I am usually so happy with apples service.

I think there should be a system to change watch straps, if they are the wrong size. and also the watch strap measurer is not correct, this needs looking at.

I would be grateful for a solution before my period for return runs out on 21st.