This sounds familiar
I remember working with a different storage vendor on different hardware. We had a crash (caused when their hardware engineer accidentally knocked the main power switch off when doing an inventory of the drives) and found that the backup procedures, put in place by the storage vendor, didn't backup all the data we needed. A crucial bit of the database didn't get saved. It said it was, and if you were prepared to wipe out the DB and restore to a cold backup taken at the weekend it would work, but the roll forward would always fail.
As it was their hardware, with their software and their backup procedure we made it there problem. It took them four weeks, but they did come up with a solution.
It was a change to the manual that said that data of the type we had was not covered in the backup process. We can't fix your data so we will accept it was a documentation failure.
Strangely that vendors hardware was scrapped at the next upgrade and they forfeited the right to bid for that contract.