If you got this from a Scubapro dealer I am stunned that they are unable to find a way to order the replacement straps for you. This is Scubapro dealer 101 level stuff here. There is a Dealer Technical Update specific to the Hydros Shoulder Straps. There is also a Shoulder Strap Replacement Work Instruction document that all Scubapro Dealers have access to.
They can order a V3 shoulder assembly kit.
Hydros Mens S, M (Midi) - 21.793.201
Hydros Men's L, XL/XXL (Maxi) - 21.793.200
There have been 3 versions of the straps. I have seen a lot of tearing in the original version. I have not seen any failures of the updated Rev 3 version to date.
What has changed with the V3 straps is below:
Changes to Shoulder Strap
Physical Dimensions of Hinge increased.
Injection Gate location moved to avoid weld line on the Hinge section.
Changes to Hinge Guide
Replaces Retaining Bar.
Controls the angle of the Shoulder Strap Webbing, preventing it from slipping on the main Hinge Bolt and ensuring that the primary load is always taken by the Webbing and not the Monprene Pad, even when the tensile force is at an angle to the backpack.