As per title. Kinda confused. On Spark, share numbers were counted as a plan. Apparently on 2D it is an add-on.

Signed up 13/12/17 to $55 pay monthly plan. Plan renews on 17/12/17. I added a share on the 15th as my share needs calls like now. The text for the share said "costs $25 each month". I was under the impression this was 1 month from the add on date since that's how it was on 2D prepay when I was last on it.

...two days later my plan renews. My share complains he can't make calls. I check my app - still says I'm sharing calls/txt/data with x number. On his app, it says he has 0 mins/0 txt but shared data still working.

I call 2D. Rep said that because my spend limit was $20 and the add on is $25, the share didn't renew. I received no messages to inform me I was no longer sharing and the app said otherwise.

With my permission he changed the spend control to $25 (to stop this being a problem next month). That didn't fix the current problem though did it - because if my add-on didn't renew, then it wouldn't have said that I was still sharing with x number. To 'fix' the problem, it looks like he just re-added my share. I received a message saying my share settings have been updated, followed by another "you are now sharing with x" txt. 

Hang on...I thought you said it didn't renew. In that case I should only have received the txt advising me 'I'm now sharing with x' like I did when I first added the share. No?

Checked my bill today - was charged another $25...  so basically I paid $25 for 2 days. 
Is this normal? I guess you can argue it's only $25, but that's pretty poor practice to not state it means 'each month along with your main plan'.