Offer available direct from Three to existing Mobile Broadband contract customers who register on a 1st/2nd Mobile Broadband minimum 18 month contract - excluding the 15GB for £15 and 0.5GB plans. The 25% discount will be applied to the cost of the line rental only, whilst customer remains on the promoted price plan. All discounts will be forfeited if either contract is in arrears/disconnects or if for whatever reason the standard price plan is terminated (the two plans have to run concurrently for discount to be applied). Offer cannot be used in conjunction with any other offer. Offer is limited to one per customer. Service limitations and terms apply. See three.co.uk for details.