What data is available when traveling to Canada, with premium plus plan?

I bought four phone lines, one for my girlfriend in Canada. I was told she would have 50 gigs (in amount) of high speed (5G) data. Two agents confirmed this for me, and even told me the towers she would have access to. Now her data is so slow, she cannot use the phone at all for data. The next three agents I spoke to have given me three different answers on what the data will be for Canada. What is the plan? And why can’t I have what I was promised when I bought it?