left luggage for more days in Shanghai

Hello,
I'm visiting china once a year and i know how stressful it is to travel from city to city with your big luggage, so i wanted to ask if you know of a left luggage service in Shanghai where i can leave my luggage for 2 days at the railway station ?
I will arrive in Shanghai Pudong Airport and will travel with the train to see Suzhou for a day und than to Hangzhou for another day and back to Shanghai for the rest of my trip and i really don't want to block the train with my big travel bag.
I can book the train tickets, if i know, if on of the railway station's has a left luggage system for more then one day.

Hope you can help me and thank you
Greetings Lili