What else are you supposed to do? Ignoring the deposit isn't really an option. It can cause a number of problems, and the problem will only get worse with time

What else are you supposed to do? Ignoring the deposit isn't really an option. It can cause a number of problems, and the problem will only get worse with time. For one thing, the tax man will notice a large enough deposit and start asking questions. Which means you'll have to prove they aren't your funds, probably with expenses involved. It could also screw up eligibility for means-tested programs. It also means you can't close the account, since you need to withdraw the funds to do so, but withdrawing those funds would leave you exposed to a charge of theft. There's unavoidable headaches and potential expenses here.