So I've bought 3pair...

So I've bought 3pairs of sneakers which one pair was too small so I changed it for a bigger size so in order for me to change it I had to send it back which I did the very next day and was told I'll get my refund in the next 5 to 9 working days which was the 5th of February up until today I'm still waiting for my refund I'm chating to them but don't get the answers I'd like so yesterday I got an email to say that it's under investigation I don't know what to do