The Everton defender has been linked with moves away.
The 22-year-old has been linked with a £50 million move to Eastlands this summer but with five days to go until the new Premier League season he remains at Everton.
It has developed into a long-running saga at this stage and Redknapp does not understand why both clubs have not yet struck a deal for the England defender.
"There are question marks over the Stones fee whether its £40m or £50m and I cannot believe the two clubs cannot get it together and get him signed," he said to Sky Sports.
But there's still some 23 days left in the window and Redknapp is certain that Stones will end up with Pep Guardiola on the blue half of Manchester.
He added: "Make no mistake, he will be there before the end of the transfer window but the sooner the deal is done the better."
Everton fans and manager Ronald Koeman must be eager to get the deal done. As it stands, it is a distraction which can't possibly be healthy for the squad as their visit of Spurs looms large this Saturday.
It is perhaps unsettling and the Dutchman will want Stones's future sorted one way or the other by this weekend.