Appalling services with no attention to requirement in reference to "the App"

Absolutely zero customer focus or attention to requirements. We have for 3 weeks now unsuccessfully tried the app but it does not work and no one on the call centre will assist unless you go on the app (which does not work....) we only wanted to change our details, now I do wonder how they will get in touch with me if my details have changed and I cannot get them to change the details. If not for the contract I would certainly rather try NETSTAR