Thanks for the reply BenMcr, and I think your comments reflect a lot of customers confusion when it comes to VM.
According to the website there is only 1 Ultimate Volt bundle and this reflects my package exactly apart from the M600 as against the Gig1 broadband even down to the O2 sim. The price I pay however is £25 more than this and it was taken out as a new 18 month contract.
I'm not sure how or why it would be classed as a "different bundle" as it's still called the same with fundamentally the same services. I think you can see why I, and probably lots of other customers, are somewhat confused.
I am happy (on the whole) with VM and have been a customer for many, many years, all the way back to Yorkshire cable but it's always been difficult to understand why customers pay different amounts for the same services even when not 'New Customers'.