New York (CNN/Money) – Peter Roedel was away on business last December when he got the call from a friend who was staying at his Milwaukee, WI home. A burglar had busted through Roedel's back door and made off with two televisions, the VCR and a few hundred dollars in cash.

Luckily, Roedel had homeowner's insurance. He filed a claim and received a check for the full amount -- $1,234.

End of story? Not quite.

This September, Roedel received word from his insurer that he would not be allowed to renew his coverage because of his "loss history" and his driving record. Roedel was stunned. The theft has been the first claim he'd filed in the eight years he had been with the company, and he had no idea that a speeding ticket would be grounds for him to get dumped.

"You think, 'I've been paying $400 a year in premiums for eight years and I had one claim for $1,200. They're already ahead [in terms of money they've collected] with me,' " he said. "It leaves a bad taste in your mouth. There was no forewarning. No nothing."

Roedel's not alone. After lowering premiums or keeping them steady for years to attract new clients, property and casualty insurers have done a 180-degree turnaround. These days, they're cleaning out their rosters with an efficiency that's leaving many homeowners, and insurance agents, stunned.

Related stories • Disaster-proof your insurance • Home insurance costs on the rise • 10 steps to lower your insurance

Many of the old assumptions about insurance – namely, you pay the premiums and they cover the losses – are now being questioned. And insurance agents are warning clients.

In fact, it's partly because insurance companies kept premiums low that they're now in trouble. Last year, property and casualty insurers suffered a $7.9 billion net loss, according to Insurance Services Office Inc., which has tracked such data for the last 30 years. Losses were exacerbated by massive mold claims as well as investment losses, which have hit the industry hard.

Farmers Insurance Group, for example, says it wants to stop renewing plans in Texas because it has paid some 17,000 mold claims this year alone and more than $1 billion for mold damage since 2001, said spokesperson Mary Flynn. What's more, the state insurance department wants Farmers to repay $150 million to customers and roll back prices after the agency said the company unfairly increased premiums – a move the company is loathe to do. "Those are huge numbers," said Flynn.

But consumers say they've also suffered losses.

Frances Manley is among those who had to file several claims after a string of bad luck. Her first, for $1,200, was made in 1997 after her home was burglarized. A year later she filed two more - one for a $1,500 leak and a $100 claim for a new antenna after a wind storm ripped through her former Arizona neighborhood. She was reimbursed for all three. Prior to that, she says she had insurance for 18 years and had never filed a claim.

"They sent me a check for $100 and I got a letter four months later saying 'We're no longer representing you,' " said Manley. "I was devastated."

Manley was able to find insurance from another company – for twice the price. But even then her troubles didn't end. When she moved to Maryland in 1999 she found insurers in that state didn't want her business. The problem? They were scared off by her claim history in Arizona, which was laid out in a CLUE (Comprehensive Loss Underwriting Exchange) report that insurers use to keep tabs on clients – and homes – to edit out potentially costly business.

"I was furious. I had a perfect record before this. But the claims were out of my control," said Manley. She eventually found insurance after going to an agent who was able to shop around and after agreeing to a higher deductible than what she originally wanted.

With the market tightening up, insurance agents say consumers will need to change their expectations. For starters, don't expect to file a claim without repercussions. It's probably best to cover the smaller losses out-of-pocket and save the claims for big-ticket damage.

One way to trim costs is by increasing the deductible, or amount you agree to pay on your own before coverage kicks in – at least $500 and even $1,000 or $2,500 if you can afford it. That said, there is a bright side to this tactic. Boosting deductibles is one of the fastest, easiest ways to trim premiums – by as much as 25 percent a year, according to Insurance Information Institute.

"If someone stole your TV set and it's $700 it's probably not worth it in the long run to file a claim because you could pay higher rates or be non-renewed," adds III spokesperson Jeanne Salvatore. On the other hand, if you had a fire in the kitchen, you should be filing that claim."