Phone returns

I bought phones from a retail store on June 25 2021 and was told the last day I could return said phones was July 9th 2021. I tried returning phones to the store and was told I was a day late and they can't do anything about it even though they were the ones who told me I had until today's date to do so. I tried contacting xfinity at 888-936-4968 and was told to try the corporate number at 800-934-6489 or 215-583-8078. One number is regular customer care who can't help me and the other is a sales line. I can't reach corporate to file a complain. Definately will be through BBB and FCC but would love to give corporate a chance to make this right.