Data is carried over but removed without usage,

I have an LTE contract which I upgraded in March to get 40 GIG day and 40 Gig night. I was told that the day data would carry over for a month. Unfortunately, after the data is carried over, the data used is deducted from the data allocated in the current months and not the carried over data which is supposed to expire in the current month. I had tried to phone the call centre, logged a fault online etc. I had logged a case and did not receive feedback. I went to the store twice to log a call back. A call centre consultant eventually contacted me and told me that the 40 GIG day data is broken down into 20 GIG day LTE data and 20 GIG inclusive data. It seems that the system deducts from the LTE data and not inclusive which is a poor excuse of why I can not use data allocated to me and thereafter it expires and is taken away. This has been happening for 2 months and has not been resolved.