Freeview viewers are complaining that they lost channels after planned changes were made to the network.
The company, which runs free digital television in the UK, warned users in advance that they might need to retune their systems today after transmitters were updated.
However, many customers say their channels have not been fully restored, despite retuning their televisions.
Freeview said anybody experiencing issues should call its advice line.
Why is there disruption?
The changes come after a decision by the government to reallocate some of the airwaves used by Freeview. Those will be used to develop new mobile broadband services in the future.
The decision means transmitters across the UK are being updated throughout 2020.
This week’s changes are happening in north-west England, north-east Wales and Creetown in Scotland, affecting about three million homes.
Viewers in these areas may need to retune their TV or box if they find they are missing channels. Paid-for satellite or cable services are not affected by the changes.
‘I could do without this hassle’
Andy Seymour from Lymm in Warrington has had problems with his Freeview since 07:00 on Wednesday morning.
After retuning, the number of channels he could watch has dropped from 120 to 16.
“It’s really frustrating because my daughter usually watches CBeebies on Freeview, while I need the internet bandwidth for working from home,” he said. “I could do without this hassle whilst we deal with the current Covid situation.”
Another viewer, who wishes to be anonymous, said they were reduced to six channels after a retune.
“I should be working today, not messing about with my TV,” she said. “What about all the senior people stuck inside due to heat? Hopefully they have radio.”
Similar complaints were made on social media by other viewers. Freeview told the BBC it is working to help these cases.
“Retuning is a normal part of Freeview and most viewers find this straightforward,” a Freeview spokesperson said.
“Information and advice on retuning Freeview equipment, including video guides for some of the most popular brands, is available on our website.
“Anyone who needs extra help, or who finds they are still missing channels after retuning, can contact the advice line free on 0808 100 0288, where our team will be happy to help.”