Looks like VHI doesn't even allow you to downgrade after the 14 days:
http://www.hia.ie/consumer-information/switching/
This is a good post BazzaDP. However, the key point is that health insurance is a contract for a defined period. So, the contract should not roll over automatically. That is why you are contacted before renewal. The 14 day cooling off period is only when you enter into a new contractual arrangement. If you had entered into a rolling arrangement then you would have had just one cooling off period and that would have been at the beginning of the original contract. In this instance, I would take the view that 28Myrtle had not entered into a new health insurance contract and that 28Myrtle did not have the intention to allow the automatic renewal. That said, the terms and conditions of the contract 28Myrtle entered into could have specified an automatic renewal unless the company received notice or payment ceased.
So, the steps I would follow are:
1. Check the TCs
2. Do not pay the first payment or revoke the bank's authority to pay
3. Inform in writing that the policy was not to auto renew.
4. Inform VHI that you wish to make a complaint formally
5. Seek final response from VHI if you are not satisfied with complaint finding
6. Refer complaint to FSO
These are not intended as advice, just a list of steps that I would take depending on the circumstances and the context for the situation.
Having had dealing with VHI in the past I have found them slow to yield to pressure during the first few stages and only become more amenable as the situation escalates along the complaint ladder.