After one month, I received yesterday an email explaining for the first time, that they have used the incorrect household income to calculate my entitlement. Apparently the error is currently being fixed and it will be ready by tomorrow.
In all honesty, after all I've been through not sure if I can believe it. I will let you know as soon as it gets resolved. Although please note this is only my experience as I understood is different depending on personal circumstances.
Hope yours will get sorted soon as I know how it feels. 🤞