Zando does not assist with exchanges

I ordered a pair of pants for my boyfriend for Christmas on Black Friday. On Christmas day when he tried the pants on they were too small. When we got back from our holiday a week and a half ago I emailed them to ask them if we could exchange them for a bigger size. After 4 emails nobody has responded to me regarding this. This is very poor customer service and I can't understand how nobody has responded to me.