I have had a gut full of energy companies who threaten to hit you with a late payment fee.
Think about it for a second, here is the company that pays me an absolute pittance for solar FIT and the energy I export is sold back to me and others at 10 times the FIT price thereby making 900% profit and they still have the unmitigated gall to threaten me with a late fee???
Someone needs to drag these silver spoon-fed cretins out of their ivory towers and welcome them to the REAL world.
Firstly it is not possible for you to buy back your own solar energy.
You only export what you don't use.
Everyone has a right to change retailers and get the best price.
You should regularly check the prices offered by retailers to see if you can better yourself.
It is written in your agreement with your retailer that late payment fees are payable and if you choose to not make a payment then the fee is legally due.
It is not that hard to estimate your weekly / fortnightly / monthly costs and make appropriate payments on your pay days. This will get you into the ball park of what your bill will be and limit the amount of bill shock you will get.
We never get bill shock as we pay water / electricity / rates off every payday and have credit on all of them giving us a buffer should we need it.
Don't whinge, do something about it rather than tell people you don't know that they can't possibly use less electricity than you do.