[5/17/17]  Gary Raia signed up for an AT&T promotion — internet and DirecTV for around a $100 a month for two years. When his first bill in July was nearly double that, he complained to AT&T.

“Every month you open up your envelope and you go, ‘OK, what’s the surprise this month?'”

“As I am talking to them, I get on the internet and I look at the special,” Raia told CBS News. “Their special is $99.99 and I say, ‘can you just look at the internet?'”

Months later, he was still paying a lot more.

“That tells me that they’re cheating people,” he said.

In an AT&T commercial a voiceover can be heard advertising: The bundle price you sign up for is guaranteed to stay the same price for two years.

AT&T told CBS News they “fully honor the terms” of their promotions.

But our investigation uncovered more than 4,000 complaints against AT&T and DirecTV related to deals, promotions and overcharging in the past two years.

One woman in Florida tried to call AT&T to have them explain her account charges.

“I keep getting bills for $79.49 and my contract says I was only going to pay $24.99 for two years,” she told AT&T over the phone.

Over three hours, five different representatives gave her five different explanations.

A female AT&T representative is heard saying: “There’s some specials on discounts that I’m thinking was actually being removed in error. Your bills are no longer combined. It wasn’t done on our end — it was done on your end.”

A second female representative said: “The pricing you were getting was because you were a new customer with the services, now you are an existing customer.”