I had some stuff shipped USPS October 31 that didn’t get handed over to Canada Post until January 31 with the USPS “reasoning” that the Canada Post strike (November 15 to December 17) was the reason. I received other items much earlier that were sent both around the same time and later from around the world. Not sure of your timing on things… maybe it was strike related and USPS didn’t want to store the package so made up a reason to send it back.
Here’s the current UPS rate sheet for Canadian brokerage services billed to receivers from page 115 of the current rate guide (USDCAD exchange rate is currently 1.43):
Even if the rate for the brokerage included services turns out to be higher than UPS Standard, aside from being slightly faster, it’s less of a f-me-around. With UPS Standard you have to confirm that you want them to be the clearance broker, and if you don’t do it fast enough, it causes chaos/returns. With the brokerage included services you get a pending delivery notice and a “pay us online now!” message. It’s less confusing for people that aren’t used to it if they can at least avoid the confirm the broker step (which often requires a phone call or you catching their call).
For a less chaotic entry to Canada from the US via UPS, I would recommend the brokerage included services and making sure that you include the recipient email address (along with their phone number) on the label so that they get email notifications about having to pay taxes/etc. prior to delivery.
When you do get to talking to an account rep at UPS, you may want to ask about prepaid import fees and taxes if you’re sending “enough” packages to Canada (that it would make figuring it out worth it). Whenever I order by 6pm from Newark it ships UPS Saver from Gaffney, SC and arrives the next morning (2 hours north of Toronto) without me having to interact with UPS or pay anything… less of a chance of customer confusion and packages coming back your way.
Or just ship from China. 
With the US-Canada tariff situation it may be cheaper, unless you’re already marking items you ship as products of China.