Customers are fed up with being told they are getting poor service "because of Covid", according to research.
Firms are being accused of using the pandemic as an excuse for long waits on the telephone or late deliveries, the UK Institute of Customer Service said.
It said that consumers were initially tolerant of delays and other issues as businesses fought to cope with the effects of the crisis.
But it said a blanket excuse was no longer sufficient.
The number of complaints about poor service in the last six months was at its highest level since 2009, according to the institute's survey of 10,000 people.
The sectors with the biggest issues were transport, local public services - such as GP surgeries, councils and police services, and telecommunications, the survey suggested.
A quarter of those asked said that some organisations had used Covid as an excuse for poor service.
"Saying 'because of Covid' is not a good phrase," said Jo Causon, the institute's chief executive. "Organisations must not hide behind this blanket statement."
She said that many businesses had responded admirably to the difficulties created by the pandemic. She said that managed queuing systems, such as inviting people to call at quieter times, was one area of success.
Others had gone out of their way to assist people during the crisis, she said. Delays in deliveries had also arisen owing to the container ship that blocked the Suez Canal in March, and border issues as a result of Brexit.
Retailers needed to be honest with customers when they started looking at a particular product about any potential delays, she said, so they were aware of how long they might have to wait to inform their decision about what to buy.
One energy customer was surprised to see that his new smart meter suggested he was using £45,000 worth of gas an hour.
The 50-year-old from Gloucestershire said the meter displayed the extreme gas usage a day after it was fitted.
While the meter was clearly not working properly, the customer said he was more frustrated that his energy company had not offered an explanation, nor sent him any kind of bill for four months.
"I would like to know what I owe," he said.
Citizens Advice has said many gas and electricity customers are still being plagued by inaccurate bills.
Pay for better service
Ms Causon said that satisfaction levels has risen slightly as firms had ultimately dealt with issues, but she said businesses needed to work on preventing the complaints in the first place.
Many customers were willing to pay extra, she said. it they knew they would get better customer service.
Bank First Direct, department store John Lewis, online retailer Amazon, and bike and vehicle company Suzuki topped the institute's table for customer satisfaction.
They were only three brands in the top 10 that also featured in the same survey a year ago.
