Non payment of account

Frank from Boland Plumbing accepted a quotation from Misting SA for a misting system for a client. He confirmed that his client paid him in full. He only paid a deposit to us and the balance was due upon completion of installation. The client also confirmed with us that they paid Boland Plumbing in full for the project. Frank has to date not answered any phonecalls or emails, this is very ********* and not business like at all.