In Relation to Selecting Customers in a Circularisation of Receivables

In relation to selecting customers in a circularisation of receivables:
(i) explain how you would use monetary unit sampling to select the customers to
circularise
(ii) consider the criteria you would use to select individual customers for circularisation
using judgement
(iii) discuss the advantages and disadvantages of using monetary unit sampling (in (i)
above) as compared with judgement (in (ii) above) to select the customers to circularise. Your answer should consider the reasons why it is undesirable only to use judgement to select the customers for circularisation.