Unlimited Texts On A Vodafone Contract?

Prior to when my contract renewed on the 4th January 2011 i was very wary of how many texts i've sent. I had sent over 3300 texts!! I have an iPhone 3GS and the plan is 300mins and Unlimited Texts and Internet. I was told that unlimited texts went up to 3000 and if i go over this then i will be charged. However when my bill came i wasnt charged a penny!! Now my girlfriend has a problem, she has gone over her 3000 right now and is very wary of texting me. Does anyone know whether she'll be charged because i wasnt charged at all for going over the allocated 3000??? Some people have said that i would be charged and some have said that i wouldnt be charged unless i keep excessivly exceeding it each month. Do does anyone know the correct outcome for any of this? Thanks.