Well since you have a phone already, I'd recommend looking at prepaid plans, for some people they are better.
However since you seem to use a lot of minutes and want 6GB data, then it seems their $60 plan is best for you. As most their prepaid plans are only decent if you don't need much more than 100MB-250MB data. and 100 or so minutes and mostly text. They are good simply because they come with CD and VM.
I would recommend calling VMC and asking to speak to retentions, or do a Customer Services Supervisor. If your account has never been in the arrears previously enough to have gone into collections (which it seems you have not been if they have already offered $10 off...) then you may be able negotiate something.
Tell them you would be willing to do the new limited time offer $60 smartphone plan IF they include a free bundle that offers CD and VM... make sure you word it like that 'one of your bundles that has VM and CD'. I work for Cogeco Cable so I know sometimes it refreshes my memory of what I can and cannot do for customers when they use terminology that I was trained by...
If they won't offer you that then ask how much it they charge for the unlock code on your phone to switch to another provider (they cannot refuse this as it is illegal to not provide unlock codes in Canada... they can however charge you).
Just by asking may get them to lean in a little more on their offer....
Also, if they can only offer 5-months or what-have-you... remember, that since you now own your phone you can go off contract with Virgin and leave when-ever, so consider that you will take what works best for you for 5-months and just try it again when they take the credits off... or just switch companies again. Who knows, if you call in every 5-months they may just keep giving you 5-months more