Peugeot 307 can't change tiptronic gearbox back to auto mode

Hi, I have just bought a 307 automatic with the tiptronic gearbox. It has the option of manual sport or snow mode problem is when I bought it it was in manual mode but I only have auto lience and would like it in auto mode so it shifts up and down gears itself but it seems to be stuck in manual mode. It shifts down gears itself but doesn't shift up. Also sport and snow buttons don't work when car is in manual mode. Does anyone know how I can reset it back to auto so it will shift up and down automatically . Would disconnecting the battery reset it? Please help, any advice much appreciated .