As a general point, try first the retailers who advertise here or in ME & MEW.
Then for ones whose publicity at least suggests they will sell small quantities to private buyers – model-engineers, vehicle restorers, etc.
My guess is that even without their inept or lazy administration, you had gone first to industrial stockists who sell only to the trade, on trade accounts, and sell mostly whole manufactured lengths. That's probably why they ignored you. I remember the tiny print on MacReady's delivery-notes explicitly refused non-trade sales.
("Our" retailers quite likely buy their stock from such firms!)
Alternatively, if you are forced to buy entire lengths, can you share it with anyone, e.g. in a club, or sell the surplus on here? Though I must admit not many will need much 60mm diameter 316 stainless-steel.