I requested whole new thing to be replaced and installed

I requested whole new thing to be replaced and installed. I did sent them the picture of what it need to replace. They give me quote. I agreed. But when they arrived they said cylinder is not included. But they still asked for R1600. I am stupidly did not realise that, When the job done. I asked them to leave the new cylinder for me. Now they are blocked me from WhatsApp messenger. Bad experience. I feel I have been ******.