If you've granted a registered Power of Attorney (POA) to a relative to sell your flat, they can receive the sale proceeds if authorised by the POA deed. If you wish for the payment to go directly to your bank account, this should be stipulated in the sale deed. If you have concerns about your agent's actions, you can jointly cancel the POA with them or unilaterally cancel it by issuing a legal notice and publishing a public notice, followed by informing the sub-registrar.