The Denver Broncos booted season-ticket holders who didn’t go to a single game last season and that led to upgraded seats for 144 accounts and about 400 seats through Monday, compared to only 14 accounts and 39 seats the previous season, the club said.

When all upgrades are made, the forced non-renewals also will allow the Broncos to make season tickets available to some fans on the 75,000-person waiting list for the first time in six years and increase its very limited single-game ticket allotment. Last season, 97 percent of the seating capacity at Mile High Stadium came from season-ticket holders, leaving just 3 percent for single games.

The Broncos said their legal “weeding out” — based on technology in the electronic ticket resale market — is putting “more tickets in the hands of Denver Broncos fans,” team spokesman Patrick Smyth said Tuesday.

But it has outraged some long-time season-ticket holders who question how the Broncos can prove what tickets were sold and why they weren’t warned of the policy.

Aurora’s Mike Fletcher, 69, had season tickets since 1977 but was told his 2016 no-show would end his annual agreement with the team. The season-ticket policy states that every account is a revocable license issued annually. Related Articles March 9, 2017 Good news for those at the front of the Broncos’ nearly 75,000 season tickets wait list

Fletcher appealed to the Broncos, saying a collapsed lung and lung-reduction surgery in 2016 forced him to sell his tickets last season. The team denied his appeal, and according to the Broncos’ ticket office, Fletcher’s tickets from 2013, 2014, 2015 and 2016 all were sold on the secondary market and used.

“I have tickets showing that I went to games, or I’d let my kids go and buy a handicap seat for myself,” Fletcher said of attending games from 2013-15.

“It’s been difficult for me to hold those tickets at times,” Fletcher said. “At times I couldn’t give those tickets away. A season-ticket holder has to give them their money in February of each year. If they’re checking anyone’s tickets, they ought to let people know that and put it in their policy.”

He added: “I guarantee you they didn’t take some of these sky-box owners’ tickets back if they didn’t go to at least one game. But how do they know that? How do we know that?”

Eric Siegler, who lives in Chicago, said he sold his seats last season to help support his cancer-stricken mother-in-law in Minnesota, who has since died. After being notified of his non-renewal, Siegler wrote an appeal letter to the Broncos, and also had his father, sister, aunt, cousin and three friends write the team. Each email was obtained by The Denver Post. Related Articles September 17, 2020 Broncos scouting report: How Denver matches up against Steelers and predictions

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“We spent a lot of time up in Minnesota and when football season came around, it was the last thing on my mind,” Eric Siegler said Tuesday. “I’m disappointed they didn’t see my situation in the same light that it was. It’s certainly not a way of supporting a fan who has been there for four decades.”

According to the Broncos’ ticket office, Siegler has a history of selling his tickets. It says Siegler sold five of eight regular-season games in 2015 and six of eight in 2014. Additionally, he elected to buy tickets for two playoffs games in 2015 and the lone one in 2014, but sold every ticket for each of those three games.

“Where’s the warning, saying ‘we have the right to revoke your tickets’ (by not attending at least one game per season?” Siegler said. “Pulled the rug right out from me — and hundreds of others. It’s not the right way to handle it, in my view.”

Smyth said some season-ticket accounts were reinstated by proving the holders sold everything in 2016 because of health issues or with the military.

“Careful consideration was given to each inquiry, including a review of previous account activity and any documentation that may have been provided,” Smyth told The Post.

Smyth added that these decisions were generally made to “reward our loyal season ticket holders, upgrade many of them, make tickets available on the waiting list and increase our very limited single-game ticket allotment.”