I very stupidly bought a 'new' Samsung S9 from  'Navel Sticker' on Lazada. The 'new' phone came with Magisk Manager already installed and every time I uninstall it, it reinstalls itself. This is preventing me using banking apps. I live in Chiang Mai. Does any member know a trustworthy shop that I can take the phone to for a permanent 'uninstall' & reinstall of factory firmware?

I don't need any members wasting their time telling me how stupid I am.

Thanks

& by the way I now know what Magisk Manager is & what it is used for...when I purchased the phone I had never heard of 'root' software.

Why don't I return the phone? I paid cash & Lazada are offering a 'voucher' for the refund & I have no desire to spend more money with Lazada.

How are you uninstalling it?  Try one of these techniques if you haven't already.

 

https://magiskroot.net/uninstall-magisk-module-twrp/

 

For something as technical as this, the best resource I know is REDDIT, Samsung sub.

https://www.reddit.com/r/samsung/

You will likely get serious but usable answers there. You will have to join to post a question. 

XDA Developers website is excellent also but it is very high level and difficult to follow at times.