I have been with Vodafone for years but they could not match or better a deal from Mobiles.co.uk but still using the Vodafone network so I switched & wanted to keep my numbers. This was ok on a Phone & Sim upgrade although only after I visited my nearest store in Inverness (a 100 mile round trip for me) The online team were diabolical & only wanted to sell me a different & more expensive contract. My other phone was changing from a SIM only to SIM only still with Vodafone but the Online team is a Retensions team & said they could only cancel my current account which took 30 days after which I could ask for a code to get my number back. Diabolical but after 3 hours and escalating up the chain the manager 'thinks' he has sorted it by 'Trying his luck' . The moral is, if you are changing within Vodafone, go into a store & if you are a business take a printed letterhead & forms of ID!