Salary Overpayment

Salary_Overpayment

I worked for a borough council and left for a planned employment break.

My salary was paid in to a main bank. During my employment, a regular monthly salary deduction was made in favour of Credit Union (based in same borough).

Four months later, whilst making a withdrawal from Credit Union, CU advised me that “payroll overpaid your salary by a month and have just re-called the monthly equivalent of salary deduction and that Credit Union have returned the money to payroll.” CU have since put this in writing.

This was the first I knew of salary overpayment (i.e. learning from Credit Union.)

I had not received any pay slip or communications from payroll and did not realise that an extra month’s pay was in my main bank.

As soon as I learnt, I offered to repay the money back to borough payroll.

My questions are what the technicalities and legalities are of:

The first I learnt of the salary overpayment was through Credit Union. Can payroll department re-call money 3+ months later from Credit Union / any bank without at least first letting ex-employee know the circumstances and their intentions? Is this legal?

Should Credit Union be giving money back three months after overpayment date and without checking with CU member first? Financial Regulations breach?

What are the data protection breaches here? Payroll employee to CU?