This procurement will have started way before the general election, as will others, and there would be a major issue with some of the existing contracts if you didn't go ahead.
Procurement rules limit the length of contracts, and for how long you can extend them, once that extension expires the incumbents are free to charge what they like, and they will, on the grounds they have nothing to loose.
Beats me why the government don't just fess up to this and get on with it.
Oh, and if they had started renegotiations for smaller new contracts, they would have taken a good 18 months to complete, increased costs hugely, potentially incurred penalties on the cancelled bid, and still left the incumbents in a we'll charge what we like until we are shot if they failed the PQQ stage.
Large contracts take a long time to negotiate, between one and two years to ensure fair play and best value.