ActewAGL told Mr Steep on Thursday morning it had sent people out to collect the bills at 6.45pm on Wednesday, right after Mr Steep and his wife had gone out for a walk.

Mr Steep was told that they arrived in the evening to collect the bills because the ActewAGL representatives had other things to do first.

An ActewAGL staff member also told Mr Steep that they utility provider was unlikely to send anyone to retrieve the bills on Thursday due to safety concerns about driving in the rain and on wet roads.

"I'm stunned. It suddenly becomes my problem. It's not funny anymore," Mr Steep said.

A bundle of about 20 bills addressed to ActewAGL customers in Kingston was also delivered to an employee of The Canberra Times on Wednesday but was not found until Thursday morning.

2CC program director Peter Davidson received a bundle of about 150 Icon Water bills on Wednesday, addressed to homes in Gunghalin and Belconnen.

Mr Steep's and Mr Davidson's own bills were taped in a second envelope to the larger package.

The bills in Mr Steep's bundle were addressed to ActewAGL customers in the 2617 postcode, which covers the suburbs of Belconnen, Kaleen, Giralang, Evatt, McKellar, Bruce and Lawson.

Several bills were addressed to houses on Mr Streep's street and other nearby homes.

The bills contain names and addresses of ActewAGL customers, unique reference numbers and show how much gas a customer is using. In some cases, it could be possible to determine from the bill if a person was receiving a pension.

ActewAGL supplies gas to around 150,000 customers in the ACT.

Mr Steep contacted ActewAGL about the mistaken delivery just before midday on Wednesday.

"I didn't want to look like I was sitting on it," he said.

Mr Steep was initially told at 1.20pm on Wednesday that two representatives from the utility provider would collect the cache of bills within about an hour.

"I'm just cranky that I've wasted a day on this," Mr Steep said.

Mr Davidson rang Icon Water at 4.30pm on Wednesday and was told to return the bills to sender. At 10am on Thursday, he contacted the water provider again and was told someone would be sent out to collect them but no collection time had been arranged.

"The guy on the other end was pretty blase about the whole thing," Mr Davidson said.

A spokeswoman for ActewAGL said on Wednesday that the company was aware of the mailout error.

"[This] has resulted in invoices that we prepare for ActewAGL and Icon Water customers being received in sealed envelopes by someone other than the intended recipient," she said.

ActewAGL said it had put on hold mail being handled by an external provider after it was notified of the mistake.

"We are investigating the matter in accordance with our internal procedures, which reflect the guidelines publicly issued by the Privacy Commissioner’s office," the spokeswoman said.

The company confirmed on Thursday that it had begun contacting affected customers and would extend bill payment times. The utility provider said it had also alerted the Privacy Commissioner's office.

Agencies subject to the Privacy Act, which include ActewAGL, must take reasonable steps to prevent misuse, interference or loss of any personal information they hold.

"We apologise for any inconvenience or concern caused," a company spokeswoman said.

The Australian Competition and Consumer Commission's Scamwatch website advises people to lock their mailboxes and destroy any documents containing personal information before disposing of them.

Scammers can use private information obtained through discarded personal documents, including utility bills, to commit identity theft.