Sold a prepaid instead of honoring my insurance

I've been with Sprint since at least 2010 and added my parents to my account years ago.  My dad broke his phone recently. He has the insurance so he went into a store to ask about replacement. They sold him a new prepaid phone with 2 months of service, but used his SIM card instead of the prepaid one. I called customer care the same day, spoke to both  customer care and prepaid departments, and was told I can return it, and as long as it was within 40 days, I would get the entire purchase returned, under buyer's remorse. We bought a phone elsewhere, and when we tried to return it, we were told there's no returning prepaid phones- under any circumstances. Customer care had lied to me. We had paid for 2 months of service and a phone, for 3 times the cost of the insurance deductible, and I still had to pay for the service on my TMobile account for the same SIM card during the same time frame.  Out $150 for the prepaid, plus the 10 months of insurance I wasn't able to use. And now I'm told I cant use the insurance to replace the broken device since a new device has been activated on that line. Anyone else have an experience like this? I feel cheated and customer service is not helping at all.