No, she shouldn't be blocking a dropped down kerb. The Highway Code's Rule 243 states that you should 'not stop or park where the kerb has been lowered to help wheelchair users and powered mobility vehicles, or where it would obstruct cyclists except when forced to do so by stationary traffic.' Parking a vehicle fully or partially across a dropped kerb is classed as an obstruction and either the police or local council can enforce the contravention. Based on the resources a particular authority has in dealing with this, attention will usually be focussed on offences that impede those with disabilities. Complaints can be made to the local police via the non-emergency 101 number, although it's usually better to contact your local council first.