scam

Yes I have a Question about my phone company I been with over 10years, the phone my son used for about 4 years , he upgraded to new phone so we all use the older phone when 1 of our phones break and have to be sent in , but today while using that same phone they shut my service off and said that the phone wasnt compatible with the service even those ive used it for a year and son has used it for 4 tears on there service . They telling me they can sell me a phone I told them i already bought a new phone through samsung ,that it wouldnt be here till the 29th of this month ,and that is why im using my sons back up phone that we always use . they tell me i cant use that phone anymore ,that i need to buy one of there , to me this is scamming people to purchase a phone that they dont need I already have a phone that works fine and i have a text and phone call come in to today and talked on it then they shut service off even tho im payed in full. thank you for you time Steve