My dc7 has a history of taking things... in shops, from dads wallet, other dc birthday candy... anything that isn’t nailed down.
It had stopped for a few weeks, but then last night money was stolen again.
Normally we have to go around in circles to get to the truth but dc was half asleep at the time of discovery, and fessed up and gave it back to go to bed.
When we tell dc off and put punishments in place it’s usually responded to with “oh well I didn’t like my iPad anyway” or “I don’t care I don’t want to go to club” 
How would you deal with it? I am at the end of my tether.