Nicholas Deakins complaint: Sole coming off shoes

I bought my son a pair of Nicholas deakin boots in August 2018 ready to start high school in September, he wore them every school day, about the 8th week of him going wearing then the sole of boot started to come away at the front, another week went past and the sole got so bad he just couldn’t wear them any more, was very disappointed as these cost me £50, my eldest son had the same pair when he was at school and we never had a problem, we thought they may have been just a dodgy pair, so a week later I ordered another pair exactly the same as the ones he had as my son lived them. These were great until the second week of wearing them and we have the same problem but this time it’s both soles one is worse then the other, im a very disappointed mum as you may understand these boots are not cheap , my son rides a bike to school and back so it’s not as if there been waked on loads just around school each day.