A criminal offence or civil?

When I wanted to move house I found a letting agent online. This company was dodgy. They took £240 off me and started lying to me then refused to redund my money. I sued them and after 5 months they were found guilty and they paid me total of £296. The small claims court suggested that I write a formal letter to close my case officially. I wrote to court but send a different letter to the defendant in which I called them 'cooks and money grabbing ar**s'. I lost my cool and insulted them. Will police charge me if they were called or is it a civil matter? Thanks