Retarding service

I called in to cancel the contract of the phone at ********** the agent dropped the line while busy talking with her when I tried I could not go through. I try to use the email thing which was advised ********** still no response. My frustration is that I had 5 days to cancel and then now it looks like I will receive the phone that I no longer need . Please advise on what to do on this regard even this morning I tried to call I can't get through because lines are busy.