Of course it is always more complicated than it looks and it is all about the 'conformity'
Like you said the directive itself
must be implemented by the member states themselves:
"Directives
A "directive" is a legislative act that sets out a goal that all EU countries must achieve. However, it is up to the individual countries to devise their own laws on how to reach these goals"
Directives are binding as to there result to achieve.
If you feel that the directive has been wrongly implemented you can always go to the national court and claim the damages from the state as directives have direct effect to nationals.
https://europa.eu/european-union/law/legal-acts_en
The directive itself only states on the 6 months:
"Article 5
3. Unless proved otherwise, any lack of conformity which becomes apparent within six months of delivery of the goods shall be presumed to have existed at the time of delivery unless this presumption is incompatible with the nature of the goods or the nature of the lack of conformity."
Meaning that any defect showing in the first 6 month is grounds for repair, replacement or refund.
After 6 months there is no burden of proof for the consumer, but for the defect to be eligible for refund, replacement or refund is must be a non-conformity with the contract.
Article 2
"Conformity with the contract
(d) show the quality and performance which are normal in goods of the same type and
which the consumer can reasonably expect, given the nature of the goods and taking into account any public statements on the specific characteristics of the goods made about them by the seller, the producer or his representative, particularly in advertising or on labelling."
That is mostly what might give reason for discussion, a hardware failure after 7 month is a non-conformity on an iPhone as you may reasonably expect your iPhone to function longer than 6 month.
A pair of sunglasses which you bought at the 1 euro-shop falling apart after 7 months will not qualify as a non-conformity.
It has to do with the value/quality of the purchased item and what can be reasonably expected.
That is what is protected in the directive and should be incorporated in to the various national laws of the member states.
For a high value/quality item such as an iPhone you may expect it to last the full 24 months.
Any way this is what keeps us lawyers busy
