Before cutting a service, OVH sends several warnings. In my opinion, the worrying point is not that OVH made a mistake, it's that important messages to the "infrastructure mailing list" of Pandas were ignored for weeks... until the post-mortem.
To be fair, if I had an agreement with a hosting provider and started to get "Your balance is too low", I'd also chalk it up to their payment/metering systems not knowing about the deal, not for the entire platform and organization to have forgotten about it.
Still I'd look into it at that point and send them an email about "Billing system not agreeing with what we've agreed on" or similar, rather than just ignoring it...