No help

Hi there, I did an order today for something on Take A lot, but then after I placed the order I realized that I want to change the gps watch for my child to a more expensive one as the one I have ordered cannot take a sim card. So I emailed the call center and they are telling me I cannot cancel the order or change it, I must not except it when it is delivered. I think it is bad service from their side to not change an order that is going to be more money for them at the end of the day.