I'm getting ripped off by my provider. Please help!

Okay so, I've been with Rogers for about 5 years now. 4 days ago I went and decided I would try for the first time ever, getting a phone on tab with them. I was told that I had 15 days or 30 minutes talk time. So an hour after getting the phone, I finally got a response from a seller on Kijiji for a phone I was interested in purchasing used. The phone I got from Rogers was an iPhone 5s, and the phone I was looking into buying used was an iPhone 5s as well. Since I really didn't want a 2 year "tab" I was talking back and forth online via email setting up a time to go buy the used 5s. In the mean time, I received about 6 calls, all which were 1 minute or less in duration. So no way I could go over my 30 minute cap right? Wrong! I purchased my used phone not even 24 hours later and swapped my sim out right away so I could actually use my phone (because once buyers remorse set in, I was afraid to use the original and go over my limit). I returned to Rogers today, 4 days later, and now they are saying there is 49 minutes used so there is no way they can take the phone back. So not only am k stuck paying full price for a Rogers phone, but I also put out a few hundred to have no term. I showed them every call I made on the Rogers purchased phone, and told them there's no more than 15 minutes. So once I put my sim in my new(used) iPhone 5s, apparently it was still registering under the term Phone, or they are trying to rip me off. I need to know if it is possible for a phone company to tell what phone your SIM card is being used in, so they can go into the calls made and see an imei number or some form of validation of what device was used to narrow down calls actually made by the "term" phone. Please help me asap. I can't be stuck with two phones like this and I can't believe that after 5 years of loving my cell phone provider with no issues, all
Of the sudden they can burn me with something so big. Extremely disappointed in Rogers. Please shed some light on how I can get them to determine what phone was used for these calls. Thanks.