1999 Volkswagen Beetle Wobbling?

When I press on my accelerator and expecially when I go up hills my car violently wobbles from side to side. Do you know what would cause this?

i took it to the garage yesterday and they put a new tire on it and said that they thought that would fix it. But it didnt. But they are going to work with me on it. But I would just like a second opinion.

Thank You!