NHTSA Complaint #11652418 — 2015 TOYOTA SIENNA

I have had this car for 7 years. Started having issues a year ago and despite bringing it to Toyota 2x, they cannot tell me what the issue is. I will be driving on a regular flat paved road when the car will suddenly brake and pull me towards the side of the road. I get the ABS code sometimes and also the slip indicator light. I've explained this each x I've brought it in and they have told me it's due to me "driving too fast" or "accidentally having my foot on the brake." LOL I am a typical soccer mom and drive conservatively and don't brake when I don't have to. It will do it on curving roads as well as straight roads. When this happens, it is terrifying! I have gone to different mechanics as well and no one can determine this issue. I've replaced the ABS sensors on this and am still having this issue. I don't know what else to do, as this is unsafe and unsafe to the extent that I no longer allow my 17 year old to drive it. Please help!!!!!!!!