H Ltd is a company providing postal and courier services to small businesses. Customers pay a monthly or annual subscription fee to use the service, plus a very small fee for each item delivered.

A year ago, H employed a new sales team. Their remuneration is dependent on the number of new customers they sign up. Sales increased dramatically in the first six months, but now difficulties are emerging such as new customers dropping their subscription once the initial period has expired; subscriber direct debits being returned unpaid; subscribers going out of business and other similar issues.

Which of the following would be appropriate to help resolve these problems?