Vodafone has adjusted many of its tariffs for the iPhone 4S, in some cases cutting the up-front charge by as much as £120.

The new tariffs, outlined today, have been issued after Vodafone decided that it wanted to "offer the best value available" - in other words, some of the deals were uncompetitive when compared to other operators. The company insisted, though, that pre-orders had not been unexpectedly poor, saying: "We’ve seen really good sales".

So, if you want to get a 16GB iPhone 4S on a 24-month contract, you could save as much as £120 on the initial outlay on a £26 per month contract, with the handset now costing £239 instead of £359.

The complete iPhone 4S buying guide

Selecting the same handset on the £31 per month, 24-month contract will save you £90; £50 on a 24-month, £36 per month contract; and a tenner on the £41 per month contract of the same length.

There are also similar reductions on the 18-month contracts, though the cheapest 18-month contract will cost you a minimum of £31 per month. There are no changes to the 12-month contracts.

There are also cuts to the price of the 32GB and 64GB iPhone 4S handsets. For full details, see the Vodafone website.

Some Vodafone customers who have already pre-ordered their iPhone 4S had been offered £59 cashback in their November bill, but the company said they would not be adversely affected by the new deals.

"We will be contacting every single customer who will be affected by more than £59 and offering them the better deal – no one will be out of pocket and in some cases, customers will be considerably better off," a Vodafone spokeswoman said.

Also, all new and upgrading consumer pay-monthly customers will be able to use as much data as they like for the first three months. At the end of this period customers can change contract if their data use is much higher or lower than their contract provides for.