I would have thought that the contract terms have been broken fairly clearly; Wabtec or ROSCO haven't provided the number agreed, to the agreed timetable and the ones they have agreed, don't work very well. They haven't got a leg to stand on. If it wasn't for the shortage of stock overall, they would have been binned ages ago.
Yes, but in my experience, commercial contracts have extensive clauses setting out what happens when terms are breached, including remedies, dispute mechanisms, and arbitration procedures. In many, the redress is through damages, not cancellation of a multi-year contract. I suspect there has already been some renegotiation and financial amendments, either through negotiation, or less likely through the formal contractual process.
The timing of refurbished sets is without dispute, but in the meantime, there are unrefurbed sets which should be available to provide a service. We're all speculating why availability of both refurbed and unrefurbed sets is so woeful, but on the former, two other operators don't seem to have the same issue, so it's not as clear cut as you suggest where the fault lies, but my guess is it is shared.