Hi There,
Vodafone call it out on their website as follows:
"Under Regulation 14 of the European Communities (electronic communications networks and services)(Universal Service and Users’ rights) Regulations 2011 an operator shall, not less than one month prior to the date of implementation of any proposed modification, notify its subscribers to that service of the proposed modification in the conditions of the contract for that service, and their right to withdraw without penalty from such contract if they do not accept the modification. "
I'd send a registered letter indicating that you are cancelling your contract per the above text and contact your bank to stop the DD.
I know Three Ireland have been flooded with cancelations due to changes on the data-side of their contracts (to head-off EU roaming changes) and the above EU legislation allows their customers to cancel an existing contract and keep their phone. C