1. There are some big supermarket for imported food, as you live in Xiasha, you should give Metro, Ole at MIXC and Choice a try
Metro麦德龙 (Address: 艮山东路355号; take bus B1 and get off at Pengbu彭埠 )
I checked Metro's online shop, https://www.metromall.cn/Product/ProductDetail.aspx?ProductID=349603
Choice西选: Basement of Block C, Wulin Intime Department Store武林银泰C座 (near Wulin Squre武林广场) http://hangzhouweekly.com/society/choice-xixuan-officially-opens
Ole at MIXC万象城 (take Metro Line 1, change to line 4 at Pengbu 彭埠 and get off at Qianjiang Road station 钱江路站)
2. If not must be imported, then there are some local substitute. if can't read Chinese, maybe ask a local friends to help find the 全麦饼干.
3. And the most convenient way is online shopping, cheap and fast