Offered two years of Xfinity Mobile data line with free ipad and $40 discount on new internet connection but discount is not applied

I was offered two years of Xfinity mobile data line with free iPad along with $40 discount per month new internet connection. However, I'm being charged $70 per month for the internet every month and promised $40 discount isn't applied. I complained with Xfinity customer service and they just kept on switching my case between internet and mobile customer services without any resolution.

I reached the customer service three times, each time spent one hour where the agent switching me back and forth. 

Could someone please help me?