Using a solicitor can be a cost effective way of recovering debts. Many firms of solicitors specialise in this type of work and process large volumes of debts for their clients every month in a cost efficient manner.
The customer may pay up straight away (or in instalments) once they hear from a solicitor.
You may have a better chance of keeping the customer if you and your solicitor do not immediately pursue the matter through the courts, but try instead to negotiate payment or resolve any dispute amicably.