Citigo Passenger Seat

Evening fellow members

I have a small problem, its my other half, when she is passenger the seat belt digs into her neck, she is only little and a booster seat is out of the question, just wondering if this can be rectified by raising the seat some how, has anyone else had this ?

There is an old thread but no solutions  ,

I had suggested trading her in for a more leggy model,   luckily my black eye has now virtually disappeared  .

Any help would be reet grand