Call from o2 offering me i phone 4

I entered into an 18 month contract(45euro/month) with O2 last november gettting an i phone for 200 euro , unfortunately lost i phone in the mean time. got a phone call yesterday from o2 saying my bills have consistently been a lot higher than 45 euro and if i wanted to increase my plan by an extra 150 mins and 100 texts at a cost of 2 euro extra per month, i asked what the catch was and they said i would be entering into a new 24 month contract, so i told them ,sorry no thanks as i had lost my i phone to which the guy said , no problem we will give you a new i phone 4 if you sign up.i agreed and he said i would recieve it withun 3-5 working days.......... happy days or am i getting the wool pulled over my eyes. as far as im concerned i was stuck with them well into next year anyway.