Unlocking my iPhone

I have an IPhoneXS that was tied to a Spectrum account that I was on with a family member as a 2nd line. She moved out of state and decided to cancel the account. At that time she had no account balance and paid off the phones associated with the account. Including the IPhone. Some time passed and I decided to try and activate the IPhone on the current account thru T-Mobile I began using when relative closed Spectrum account. T-Mobile said it was no problem if phone was unlocked. I had relative call Spectrum to have that done. They refused to do so cuz the account was closed and the account was no longer in their computer. They wouldn’t have let her close the account if there was balance on phones or account so they know everything was paid. After arguing with them to do it, which they refused and said I could only put phone back on their network as a new phone. I tried an online company and they said Spectrum denied them unlock code as well on imei number. Is there anyway to get the IPhone XS unlocked at this point? The phone is in great shape and I don’t have money to buy a new phone to put on plan. (The phone I had on plan was ruined.) I need this IPhone unlocked.