WM – Waste Management complaint: Partial service are being provided

My sisters have lived in this address since 1992, and have been using W.M. For the garbage disposal services, as of last 2 months the garbage can(provided by W.M) has been particularly disposing .1/3 to 2/3 if the bags remain in the can, after the garbage disposal truck stops by. My sister made numerous complaints however the response they have been getting from W.M. Is; the garbage bags being forced in the can are too many and excessive forces are being used to force the bags in the garbage can. This is a totally irrational response from W.M. Since my sisters both are over age of 70’s with severe disabilities?? This a completely bogus explanation to get out of doing their job properly. Unless my Sisters are female versions of Superman ( that I am not aware of it) there is no way they would be able to force pack so many garbage bags in a 50 Gal. Garbage can.
This happened to my mother when she was 90 yrs old living with them about 5/6 yrs ago .I decided yo monitor our security cameras as well as I did recently. I found out when the driver picks up the can, he doesn’t bother to shake the cans at all to make sure all the garbages have emptied from the cans prior to placing them on the ground. I am finding the kind of negligence as I found it 5-6 yrs.ago. I can understand that there are certain employees do try to short cut their jobs, however I can’t accept that other employees in the office support their stories.
If this matter is not resolved immediately, I will be filling complaints with attorneys general’s office, state agencies and take legal actions against WM for providing partial services. Thank you