The perils of taking a rocket launcher to a water pistol fight

I don’t like to have regrets in business- I think everything we do and everything we go through, good and bad, is a learning experience and life is way too short to live in the past. But there is something I did about 5 years ago that I still kick myself over. I was engaged to provide debt collection training to a major insurance brokerage here in Queensland. The session was a tremendous success and the feedback I received from all the attendees was great. It went so well and they all learnt so much that I was invited back again in the future to provide some one-on-one training to one of their staff who was particularly struggling with collections. Excited about this opportunity, I left them that day, came back to the office, issued my invoice for payment and submitted it to their accounts team. About 4 days later I still hadn’t been paid, despite their accounts person assuring me it would be done the same day. They owed me $2000 which was a lot of money for me and the business back then. By day 7 I was beginning to get a little worried but also slightly p***sed off. So I decided to bypass their accounts team and go straight to the directors of the company- big mistake. This was a massive company with a household name and the director I spoke with was not happy that I threatened legal action if it wasn’t paid that day. She assured me she would look into it immediately and an hour later it was paid. Unbeknownst to me, there was a glitch with their accounts payable system and I would have been paid that day anyway had I just been a little patient. All my ridiculously heavy approach had done however was guarantee that I would never be engaged by them again and I never was invited back for the extra training.