The mobile network said it was doing so as part of its support measures during the coronavirus pandemic, a day after they were called out for increasing their tariffs, BBC reports.
Customers considered “vulnerable” will be automatically upgraded, it said, while others can apply.
Many mobile operators and other services raise their prices in April each year, by an amount linked to inflation.
Other phone operators had already announced their price increases before people began to lose their jobs during the coronavirus shutdown.
“We appreciate now is not a good time to be communicating a price rise,” a spokesman said of the 2.5% increase.
The “vulnerable” customers who will automatically be upgraded to the unlimited data scheme include those with declared disabilities or mental health issues, “among other things”, a Vodafone spokesman said. Those customers will receive a text telling them about it.
As the pandemic spreads across Europe, Spain has just recorded 838 deaths in 24 hours from coronavirus, a new daily record bringing the total number of deaths to 6,528, according to health ministry figures.
The number of confirmed cases in Spain has now reached 78,797.