The power companies can choose to fully or partially reinstate the electricity supply or keep it switched off!
My husband and I discovered that over 20 years ago, when we had a power cut on New Year's Day! My husband's mother who was nearly 80 and in poor health was staying with us at the time and my 2 children were both under the age of 10. The power was off completely for several hours, and as the time clock for the gas central heating requires electricity, the house soon became absolutely freezing!
My husband called our electricity service provider to complain, and to ask if there was anything they could do, given our situation. There was! Within 30 minutes, we had power fully restored! Meanwhile, almost all our neighbours in the street were left without power until the next day!
This shows that it pays to complain - you don't ask, you don't get! ?