That sounds like an entirely unpleasant experience.

Reading your post inspired me to write a wryly informative yet droll linguistic comment for your edification and enjoyment (and my own entertainment). However my comment may strike you, in any case, I am certain it is entirely unrelated to the miserable experience you describe in your comment, as well as the content of the original post. Ready? Ok.

At face value, the message is entirely clear from what you've written. The restaurant owners required you to use a tablet to browse the menu items they have on offer, and that tablet had a particularly poor user experience.

However, I found your last sentence quite ambiguous, and interestingly so:

...it was an iPad which only pensioners use,...

I see at least three interpretations of this sentence fragment:

1. iPads, as a category in general, are devices used by pensioners and no one else. (Note: my guess is that this is what you actually meant)
2. This particular iPad had specific features that indicated all preceding users were pensioners. You don't mention any of these features, but perhaps there were fingerprints of denture glue on the screen, or a distinct odor of moth balls.
3. The particular iPad was restricted for use by pensioners only and no others, in which case you've broken the law and the Police Nationale are on their way. The laws are strict in France, I don't make the rules.

Okay, yes yes, readings 2 and 3 are hyperbolic; however, this was intentional, partially for the lolz, but also to convey a sense of saliency for the respective interpretations.

The internet comment section is such an interesting treasure trove of human language. See, in typical language use (by typical, I specifically mean how language evolved, as humans in the bush, making sounds at each other around a fire), there are a multitude of cues that go beyond the simple string of words, collectively referred to as "pragmatics." These are nonverbal cues like body language and facial expression, but also verbal cues like prosody, intonation, and stress. There are also "discourse" level aspects, like how we can follow the overall point of a speaker. (As an example of discourse, I told you up front that my comment would be somewhat amusing and educational, and hopefully I have delivered that to you - if I haven't, well it's still the discourse level pragmatics that underlie your feeling of annoyance or disappointment.)

Another pragmatic element is shared knowledge. Off the bat, we both have some fluency in English, but pragmatically (ha, see what I did there?), that's a given, but it goes further than that. Friends and family have a history of shared experiences. On the Internet, well we're both Lemmings, so we likely have an aptitude for technology, as well as other niche hobbies or interests. Shared knowledge is more or less anything that one speaker can assume about another on the basis of experience or overt group membership.

This is what is so interesting about Internet comments though - the pragmatics of language are often missing! This sentence might have been 100% clear if we had more shared knowledge. Perhaps all that was needed was hearing you say it, which would have carried prosody and stress.

Anyway, I hope you learned something interesting.

Was the food good at least?