The most they credit card companys (or any financial instution) are allowed to charge in Canada is 29.99 APR, this is why the laws changed regarding pay day advance services a few yrs ago.
Ive never heard of a cards rate doubling if you miss a payment. Sometimes the companys offer special rates promotional rates for a period of time, like 2.9-4.9%, and if you miss a payment your rate will defer back to your regular intrest rate.
I've got a sob/horror story similar to this.
About 5 years ago or so, I was laid off from my job. I found out that I had special insurance, where my credit card company would make my minimum paymetns for me until I became employed again.
I was unemployed for over a year, and never got any credit card statements, I figured all was good.
However, they were only making my interest payments or something like that, not other mystery penalties or service charges ( i no longer used the card at all).
To my horror, when I became employed again and phoned about my statements so I could start making my payments again, I now owed them just under 10,000... (my limit had been 5500). The other miscelanious charges and penalties took me over limit they told me, and my new interest rate was just under 29% - but they were still only covering my minimum payments at my old interest rate. The extra interest and penalties added up very quickly apparently.
Oh, and they upped my limit for me, without telling me, or sending me any statements. (thanks alot credit card company) 30% on $10,000 is a lot of interest on a credit card I originally had at 6% and for $5500 (and which was sent to me at christmas, on a year where I really needed some extra money....I just had to sign it to use it - Thanks alot again, credit card company)
I still feel like I should have looked into it more, I felt wronged.. but I guess I should have asked for statements right away (rather than assume everything was alright) I wass able to get a loan to pay them out in full, and tore up my credit card.
It was an MBNA mastercard, by the way.