Why did this happen and can someone tell me and help me how long will this be.

So yesterday I was playing chess and suddenly I got a notifications saying my account has been banned due to sandbagging and infact when I was playing my connection was so bad that it kept opening the same tab again and again and it was crashing so then I got this email and now I have to wait seems pretty unfair for connection issues so can someone help me here and why this happened please let me know