l'ordonnance, lunettes and lordie what next?

[mint]

I posted about this rather urgent problem yesterday on my previous thread about lunettes but, as I have unusually had no response, I thought I'd start a new thread.  BTW I really need advice or at the very least some suggestions.

OH saw his ophthalmologue, had a new ordonnance for glasses and went to an optician to be kitted out.  Turns out the glasses were no use as everything was blurred and they were obviously dangerous to use.

Went back to the shop and were told to see an optometrist who would check his prescription against his new glasses and at the same time advise some "ré-education" exercises if these were needed.  Said it was no use re-doing the lenses if the prescription was not right in the first place.  Said to come back after all that was done and they'd look at the matter again (no pun on "look" intended)!

So did as told and it was found that the prescription was too strong and a new prescription was issued.  Went back to the shop, thinking they would now go ahead and put in new lenses.  Yes, they said, we could do that and the cost is 310 euros.  No mention of paying was made before then.

What I need to know is this.  If a prescription does not conform and brand new glasses were provided which then didn't work, is it up to us to pay?  Are there règles written somewhere that explain what is correct?  We will, of course, pay for new lenses if we have to but I thought it worth asking on the Forum.

Any thoughts, suggestions, links to sites anybody, svp?