Horizon’s managing director heard the broadcast whilst driving and immediately tried to get the transmission stopped, the report said.
Ofcom said there was evidence that the transmission provider was asked to turn off the Horizon Radio service on DAB at 18:32 BST and again at 18:43, at 18:44 and twice at 18:47.
The correct service was restored at 18:50 BST.
In its ruling, Ofcom said Horizon Radio took swift action to stop the incorrect stream from being broadcast.
It also made an apology shortly after the incident, and it contacted the regulator to inform it about the situation.
Ofcom concluded it did “everything in its control to minimise the impact of this incident” and the matter was now resolved.
Horizon Radio said its technical manager now maintained all its streaming output and it no longer used the services of third-party stream providers, nor would it in the future.