☛ Contact customer and remind about their payment politely

☛ Contact with an overdue payment reminder

☛ If the customer still fails to pay the payment as per the terms of the payment, send them a final notice

☛ Even after sending final notice if still there is no response from customer, try to make direct contact and ask for payment again

☛ After failing all options, if the customer still resent from payment then send a formal letter of demand. This could be the last option as it may spoil your relationship with the customer.