The Upper Law Society of Ontario will deal only with cases of bad behavior of a lawyer and matters where they acted unprofessionally and/or against their ethical codes.
https://lso.ca/getdoc/8626e365-d1a8-4cdc-9ee4-63a8054a3417/how-to-make-a-complaint
For anything dealing with overcharged fees and inapropriate detailed invoice, you must take the steps to have his services revised under an assessment.
If you are talking just about a few hours difference for some thousand or less dollars, don't waste your time (or the assessor's time) with your complaint.
I had hired a lawyer from the law firm Sicotte & Guilbault from Ottawa (the boss of the shop) once for my case on Appeal in Toronto. When we met, he was very vague and evasive on the fees he was to charge me on reviewing my documents that I had prepared. He only changed a few paragraphs for legal wordings. Then I filed everything with the Appeal Court without his help. He then contacted me to plead my case in my favor but once again, was very unclear with the fees but was to be somewhat low, around the X$. He sucked real good at pleading even though we won but his fees went to XXX$. Then after, he sucked real tight in taking care of the Power of Sale of the property in order to get my share of the equalization payment.
I ask him to provide all his invoices with full details for an assessment. He was mad enough to call and insult my wife over the phone. I was very determined to have his fees reassessed. Then we had a conversaton over the phone where he said he was sorry but I kept on saying that he had overcharged me as his services were poor and lacking at several points. I did not pursue my complaint but did a formal review of his services with my signature on Google. Don't forget, the social media is the #1 place for justice before the court system itself. The judicial system will hide the evidence from the view of the public but the media won't. Don't waste your time with the Law Society, make the public know about that lazy/crook lawyer.