I don’t think your own lack of research and taking the manufacturers figures at face value would be sufficient reason to terminate the contract. At least not without paying the early termination fee.
I also think that you’re somewhat out of date with public chargers these days. Presumably you use motorway at least part of your journey? Services have Gridserve chargers that all take contactless and are rapid enough that you’re Megan would go from something like 30% to 80% in the time it took you to have a coffee. There’s also a plethora of rapid chargers a mile or less from loads of motorway junctions these days.
I bet if you gave this forum the route you use you’d be provided with a list of multiple charging stations you could easily and quickly use for that one top-up you need on the return leg.