Someone tried to switch accounts with me !

for some reason ive been losing connection to the CoC server recently and today i finnaly know why !
as i was playing CoC it asked if i wanted to confirm to switch to a new base. with all the progress i had as a 1/2 maxed TH 8 i obviously said no to being demoted to a TH 6 account.
What would you guys do if this happened to you and how can i fix this issue.
It seems as though people are trying to find a way to steal accounts and it needs to stop !

Also the person trying to switch accounts with me is known as LucasE

you have 2 things to think about:

1. have you given/lost any of your devices with clash of clans on it?
2. has a friend had a hand on your device that you play on recently?

i would also sync up your clan to gamecenter if you haven't already