about model U 8812D
I checked the Huawei U8812D aka. Huawei Ascend G302D but did not find any copy of the user manual online. I compared the Huawei U8812D with the Huawei Ascend G312 and they are very similar, with the difference only the processor and internal memory. You can try the Ascend G312 manual. Hopefully it can be of help to you.
Download the manual from the Huawei Ascend G312 product page.