Tom tom GO 510.......any one got one??

[blossomsmine]

I have had my tomtom a year or so and it needs updating i think. I went to do it on the computer but it will only update safety cameras, so i did that. I need to update maps as i was driving in a city recently and it kept taking me down new one way streets, not very nice!! Any one know what i do, do i need to buy a new map and if so how do i do it?? Sorry to be useless but i am so 'untechnical' thanks.