Discovery did not pay full cash back amount

Discovery Insure did not pay me the full cash back they owed me for this month. I sent them e-mails, including copies of all my receipts, but they didn't pay me the outstanding amount. I sent e-mails on last week Tuesday. they said they would get back to me in 24 hours. It has been a week and I have still not heard from them. Your customer service leaves much to be desired.