Braided Solo Loop strap becoming loose

I am already on my second strap - 45mm Midnight Braided Solo Loop - Size 9.

It is frustrating that the straps change their size and are totally loose and cant be used anymore. When purchased they were tight on my wrist when purchased and were approved by the apple-store sales person. One purchased in the US and second in UK.

This is surly a design flaw in the product.

they were both purchased at full retail price.

please revert