Vodafone Promotion SCAM

Claiming to be from Vodafone asking if I had any complaints or issues Offering 45% discount on current network bill, remain for 12 months on existing account and services. He requested to confirm how much I paid last month. I said I cannot remember, something like £38 per month approx. He then confirmed my last bill was £39.50 and new bill is £21.73 from the next month for 12 months on the same existing contract. He also said they would give me 500 international minutes on my telephone. I said how can you do that? I do not have a telephone contract with Vodafone? I asked what my address is if this genuinely Vodafone, he said he would send me verification and promotion to my email address (gmail) I explained I do not use a gmail address for personal use. TOTAL SCAM!!!