I now have a BT box as I was fed up struggling to get my Chromecast to work efficiently, to enable me to watch the Sport without constant breaks. I also have 'super fast'! Broadband. With a fairly up to date TV, is it not possible to watch the App directly on TV, or do you still need to use the Cast method?
Depending on your account setup, it may be the case that you are only available to watch via Chromecast as a means. Chromecast has proven to be one of our more stable platforms so surprised to hear that you have had trouble. Sadly, I do not have the correct level of access to verify your account setup but hopefully one of my colleagues will pick this up shortly.