Bad service

My brother is an electrician and was approached by GL Insurance Brokers on 3 and 7 July 2024 to do a quote and reports for a client of theirs. His invoices was submitted on 20 July. He dealt with Tato and when he was not happy when Tato advised he will only be paid in 30 days, he blocked him. I contacted Tato on 26 August and he referred me to Gencom who advised they do not speak to clients. I was not impressed and called a senior at GL Insurance who put me into contact with Rohan Miller. I discovered that Gencome was not happy with the invoices, which was correct and submitted. When I followed up, I was advised that the invoice will only be paid in 30 days. They do not take into consideration that they had the invoice since 12 July as the correct one was only submitted on 30 Aug 2024. Bearing in mind no one communicate the issues with the invoice prior to August 2024. I believe this is a delaying tactic not to pay