I was LIED to about Xfinity $30 discount!!

I have had Xfinity internet since 2016. After much solicitation and discussion, I decided to wait my mobile devices over to Xfinity. Not only was that a complete nightmare, but they also told me I would have a $30 discount on my internet. I switched two lines last week. This week, I went to look at my bill.  They added a third line, without my permission or knowledge, and I was told there was no $30 internet discount, it would only be $10!!!! Bait and switch?!?!? I have been on the phone all day trying to get this resolved to no avail.