Nimble group is lying and does not want to give me my paid up letter

Nimble group told me if I settle my account with the black Friday deal of there's which was what ever ammount i pay they will match it they said they will send me my paid up letter I paid them on the 24 November 2024 and send them the proof of payment aswell now they have alot of excuses of why I can't get my paid up letter they said the promotion ends on the 8th of December so there after they will send my letter now ther is excuses af excuses my credit score drop after I paid them my last money I had please someone help me.