Some Freeview viewers in Bristol, Somerset and Gloucestershire have complained that they were left with Welsh television after re-tuning.
Viewers were told to adjust their TVs as the first part of digital switchover got underway on Wednesday.
A Digital UK spokesman estimated there were 30,000 homes in the West which might be affected by the problem.
"By going to the digitaluk.co.uk website there is a guide to re-tuning manually which will resolve this."
Bill Taylor, south west regional manager for Digital UK, said the problem was "just an outcome of the physics of broadcasting".
Mr Taylor said that in some homes the equipment will pick up both the signals from the Wenvoe transmitter in Wales and the Mendip transmitter.
Televisions in homes close to the the Bristol Channel and Forest of Dean may also pick-up the signal from Wales.
"I understand people's frustration, but it is not the case that anyone has made a mistake," he said.
"It is a natural consequence of living in an overlap area between two transmitters."
But some viewers who have retuned found they have lost Points West and were instead watching BBC Wales.
A number have e-mailed or phoned the BBC in Bristol to complain.
The BBC TV services for existing Freeview viewers have now moved to new frequencies. These can be restored by manually re-tuning TVs and boxes.
Details on how to do this can be found on the Digital UK website.