New account billing issue

I have a new wifi account and signed up for the $70/mo 1gig plan and my bill is showing it will be $80. The chat and customer service person keep telling me it will take up to 45 days, but what I read that’s when you’re making the change to billing on an existing account, not when creating a new account with that promo. They said I won’t get the $10 back, and it may not even be corrected on the next bill. How do I get to pay my advertised price of $70 if no one will address it?