Good stuff about aircraft paperwork, but we must always remember that to be able to conduct and verify maintenance and servicing the aircraft must first be declared airworthy, as that is what facilitates serviceability.
It was not a case of simply sending the gliders to whatever repair shop. First, the airworthiness baseline had to be stabilised. To MoD/MAA, that is a major task, especially when there is no Safety Case and at the same time trying to hide the fact the failings apply pan-MoD - a political consideration post-Haddon-Cave. That would have slowed process. I cannot speak for the quality or performance at the various contractors, but their task is relatively insignificant.