For anyone interested, I maintained a server within the affected DC.
OVH provided 3x the price of the service for the downtime. But for the recovery we needed to buy a new server from them as our backups were only accesible from dedicated machines...
At the end we basically received 2x the price of the server when discounting the temp machine.
Communication during the downtime was not bad from OVH side, taking into account the huge amount of affected servers.
At the end, as a small customer I cant do or ask for much more. As it's not worth neither the money or the time.
IMHO, 3x is not covering any business loses for anyone. We got our own backups within the OVH network and it took 3 additional days to be able to access them as the network was a mess after the fire. That for some business is going to be a huge sum.
https://www.odinflash.com/odinchangelog