Old Phone Still Reflected on my Account

I purchased a new phone from Amazon and went to the Xfinity store to have the SIM card changed from the old phone to the new phone. However, the old phone is still reflected on my account three days later. I have called Xfinity Mobile tech support and they were not successful in resolving this issue. I went to the Xfinity store today and they basically said there was nothing they could do since the phone was not purchased from Xfinity. This does not seem like a logical answer. Can anyone help? Thanks.