Slow speed on Huawei HG633

Hello, i have a really slow connection since TalkTalk sent me SuperRouter Huawei HG633. I have SuperFibre up to 38mb, while it shows max speed around 7mb... It's not what i'm paying for. Everytime i write with "helpers" on the chat, they just throw some copy/paste texts . 

From what i know -but i may be wrong- there is an firmware update 1.16t for this router, but it must to be applied by , but also it may be sent another router HG635 which seems to not having any problems like HG633.

Please respond ASAP

I'd like to add that i've done speedtests on few devices on a cable, and also wirelessly. Everytime it's the same.

I also would like to note, that on huawei hg533 with BT Openreach, i hadn't had any problems at all.