What's wrong with my sat nav?????????????

i've only just bought it and now sony want �42 off me to update the bloody maps!! its a nv-u50, and it doesnt even take full postcodes!! what with ps3 ad psp and the sony erricson i-phones that are market leaders, why have i put my faith in someone who not only want to charge me for the satnav in the first place, but then also want an extra 42 bloody quid just to make the damn thing work properly!!!!