@TomThumb I’m a bit confused (not difficult), but who has been driving the Motability car during the period of your daughter’s ban? Assuming that it’s yourself, or another family member, rather than have all the worry of trying to buy and adapt a private car, could that arrangement not continue?
Unfortunately, a driving ban, especially for things like dangerous driving, drink or drug driving, is usually only the start of the persons issues. As you have discovered, some insurers won’t touch drivers with those convictions and those that do will charge thousands for the privilege as the risk profile is so high.