Unwanted and not-agreed AT&T Dtv Promotions/T-Mobile Referral Program

2022/5/26 

AT&T Dtv Sale Agent misled me to the promotion deal I did not want.

He was explaining the options and I was just telling him my preference.

I never accepted any option but he e-mailed me an invoice based on my preference.

I told him I did not want the promotion deal but he said nothing he can do since the invoice was emailed.

He was repeating that I have to pay the invoce....

What I can do to reject the deal I did not want?

Thanks!