If you look at this link, you will see the Serco contract information for glider maintenance:
£9.4M - Feb 2008 to Mar 2015.
I wonder what the case (if any) is against Serco for the issues…?
Of some interest, there was a PQ about the number/value/length of Serco contracts to MOD.
Found some guideline refurbishment costs from the ACO Flying Review, Jan 2013.
Finally, some interesting information concerning possible use of BGA facilities (& also some other interesting background information) in the Flying & Gliding Study, Dec 2012.