What price should I put on that? What price is it worth to Gandi? Are they going to offer me a year's free domain registration with them? That offer has negative value to me; I wouldn't take it unless paid a lot of money to do so. Are they going to offer me a pile of money (no they aren't, it's not worth it to them). So what exactly are they going to offer here to right the wrong?
The point here - which the top of this thread made, but maybe it wasn't explicit enough for you - is that services such as domain registration can easily have effects disproportionate to the cost of providing them. If all of Google's domains were deleted tomorrow, the cost to Google would easily exceed ($10 x number_of_domains). So a poor service experience can easily do more damage than the sum total of all revenue ever received from a particular customer. Thus the commenter looking for companies which try hard to provide good service. Gandi.net is not such a company, in my experience. (Hint: companies which provide good service have email addresses and phone numbers to contact them.) That's my only comment.
It really irks me when people use this sort of logic. I can't say what their support was like several years ago, but I have heard nothing but fantastic things about their support and service offerings over the last 2-3 years, and not by the general web user, but by us "nerd elites". So dude, chill the Eff out and don't be such a hard ass against something that happened admittedly several years ago.
Oh, and you call out "what could they possibly provide me after so many years", well you have a direct response from a customer support person who has offered the ability to "make it right". You do not know what they would be willing/capable of doing until you ask. So get off your high horse and just ask. They might surprise you...
/rant
It's not that I don't believe companies can fix their problems; it's that I believe in feedback and the one form of feedback companies cannot ignore is revenue. It's Darwinian - if a company screws too many customers, they die.
So I haven't used Windows since Microsoft's deeply unethical attacks on OpenDocument; I moved all my US domains from GoDaddy to NameCheap after the elephants broke that camel's back; and Domain Central have all my Aussie domains after NetRegistry de-registered a heavily used domain name in very dubious circumstances.
I once let a domain expire by accident, but since it was obscure the squatter who snatched it let it lapse after the ~45 day ICANN "trial" period that used to be a boon to evil squatters (AIUI, IIRC). So I just registered it again myself.