How about turning the table on mum and face to face or at the very least over the phone...I hate texting stuff like this....ask her how she suggests you curb this behaviour. It's not you taking orders, or her being your boss, this is about putting her on the spot and coming at her from a different angle. If she thinks your suggestions are no good or aren't worth her time then make her think she is in the drivers seat making the call. Obviously you can dispel any ridiculous suggestions with an explanation along the lines of "In my experience...." This may prevent her from being so defensive and she may change her tune. She can't possibly think that no action of any kind shouldn't be taken????