I had the repair kit fitted to my Hydro Unit a year ago and it's still going strong - job took a couple of hours.
My bill said the following:
B220.127.116.117.896 646 HYDRO UNIT REPAIR KIT £144.68+VAT
Also it says earlier:
Carry out control unit survey, DSC pressure sensor fault, supply and fit DSC hydro unit repair kit £174.80+VAT